martes, 30 de junio de 2020

8 Useful Websites for Hackers

  1. Packet Storm: Information Security Services, News, Files, Tools, Exploits, Advisories and Whitepapers.
  2. Metasploit: Find security issues, verify vulnerability mitigations & manage security assessments with Metasploit. Get the worlds best penetration testing software now.
  3. Phrack Magazine: Digital hacking magazine.
  4. KitPloit: Leading source of Security Tools, Hacking Tools, CyberSecurity and Network Security.
  5. The Hacker News: The Hacker News — most trusted and widely-acknowledged online cyber security news magazine with in-depth technical coverage for cybersecurity.
  6. Exploit DB: An archive of exploits and vulnerable software by Offensive Security. The site collects exploits from submissions and mailing lists and concentrates them in a single database.
  7. Hacked Gadgets: A resource for DIY project documentation as well as general gadget and technology news.
  8. HackRead: HackRead is a News Platform that centers on InfoSec, Cyber Crime, Privacy, Surveillance, and Hacking News with full-scale reviews on Social Media Platforms.

jueves, 11 de junio de 2020

RECONNAISSANCE IN ETHICAL HACKING

What is reconnaissance in ethical hacking?
This is the primary phase of hacking where the hacker tries to collect as much information as possible about the target.It includes identifying the target ip address range,network,domain,mail server records etc.

They are of two types-
Active Reconnaissance 
Passive Reconnaissance 

1-Active Reconnaissance-It the process from which we directly interact with the computer system to gain information. This information can be relevant and accurate but there is a risk of getting detected if you are planning active reconnaissance without permission.if you are detected then the administration will take the severe action action against you it may be jail!

Passive Reconnaissance-In this process you will not be directly connected to a computer system.This process is used to gather essential information without ever interacting with the target system.

More articles


Group Instant Messaging: Why Blaming Developers Is Not Fair But Enhancing The Protocols Would Be Appropriate

After presenting our work at Real World Crypto 2018 [1] and seeing the enormous press coverage, we want to get two things straight: 1. Most described weaknesses are only exploitable by the malicious server or by knowing a large secret number and thereby the protocols are still very secure (what we wrote in the paper but some newspapers did not adopt) and 2. we see ways to enhance the WhatsApp protocol without breaking its features.


We are of course very happy that our research reached so many people and even though IT security and cryptography are often hard to understand for outsiders, Andy Greenberg [2], Patrick Beuth [3] and other journalists [4,5,6,7,8] wrote articles that were understandable on the one hand and very accurate and precise on the other hand. In contrast to this, we also saw some inaccurate articles [9,10] that fanned fear and greatly diverged in their description from what we wrote in our paper. We expected this from the boulevard press in Germany and therefore asked them to stick to the facts when they were contacting us. But none of the worst two articles' [9,10] authors contacted us in advance. Since our aim was never to blame any application or protocol but rather we wanted to encourage the developers to enhance the protocols, it contradicts our aim that WhatsApp and Signal are partially declared attackable by "anyone" "easily" [9,10].

Against this background, we understand Moxie's vexation about certain headlines that were on the Internet in the last days [11]. However, we believe that the ones who understand the weaknesses, comprehend that only the malicious server can detectably make use of them (in WhatsApp) or the secret group ID needs to be obtained from a member (in Signal). As such, we want to make clear that our paper does not primarily focus on the description of weaknesses but presents a new approach for analyzing and evaluating the security of group instant messaging protocols. Further we propose measures to enhance the analyzed protocols. The description of the protocols' weaknesses is only one part of the evaluation of our analysis approach and thereby of the investigation of real world protocols. This is the scientific contribution of our paper. The practical contribution of the analyzed messengers, which is the communication confidentiality for billion users (in most cases), is great and should be noted. Therefore we believe that being Signal, WhatsApp, or Threema by applying encryption to all messages and consequently risking research with negative results is much better than being a messenger that does not encrypt group messages end-to-end at all. We do not want to blame messengers that are far less secure (read Moxie's post [11] if you are interested).

Finally we want note that applying security measures according to the ticket approach (as we call it in the paper [12]) to the invitation links would solve the issues that Facebook's security head mentioned in his reply [13] on our findings. To our knowledge, adding authenticity to group update messages would not affect invitation links: If no invitation link was generated for a group, group members should only accept joining users if they were added by an authentic group update message. As soon as a group invitation link was generated, all joining users would need to be accepted as new group members with the current design. However there are plenty ways how WhatsApp could use invitation links without endowing the server with the power to manage groups without the group admins' permission:
One approach would be generating the invitation links secretly and sharing them without the knowledge of the server. An invitation link could then contain a secret ticket for the group and the ID of the group. As soon as a user, who received the link, wants to join the group, she can request the server with the group ID to obtain all current group members. The secret ticket can now be sent to all existing group members encrypted such that the legitimate join can be verified.

Of course this would require engineering but the capability of WhatsApp, shipping drastic protocol updates, can be assumed since they applied end-to-end encryption in the first place.

[1] https://www.youtube.com/watch?v=i5i38WlHfds
[2] https://www.wired.com/story/whatsapp-security-flaws-encryption-group-chats/
[3] http://www.spiegel.de/netzwelt/apps/whatsapp-gruppenchats-schwachstelle-im-verschluesselungs-protokoll-a-1187338.html
[4] http://www.sueddeutsche.de/digital/it-sicherheit-wie-fremde-sich-in-whatsapp-gruppenchats-einladen-koennen-1.3821656
[5] https://techcrunch.com/2018/01/10/security-researchers-flag-invite-bug-in-whatsapp-group-chats/
[6] http://www.telegraph.co.uk/technology/2018/01/10/whatsapp-bug-raises-questions-group-message-privacy/
[7] http://www.handelsblatt.com/technik/it-internet/verschluesselung-umgangen-forscher-finden-sicherheitsluecke-bei-whatsapp/20836518.html
[8] https://www.heise.de/security/meldung/WhatsApp-und-Signal-Forscher-beschreiben-Schwaechen-verschluesselter-Gruppenchats-3942046.html
[9] https://www.theinquirer.net/inquirer/news/3024215/whatsapp-bug-lets-anyone-easily-infiltrate-private-group-chats
[10] http://www.dailymail.co.uk/sciencetech/article-5257713/WhatsApp-security-flaw-lets-spy-private-chats.html
[11] https://news.ycombinator.com/item?id=16117487
[12] https://eprint.iacr.org/2017/713.pdf
[13] https://twitter.com/alexstamos/status/951169036947107840

Further articles:
- Matthew Green's blog post: https://blog.cryptographyengineering.com/2018/01/10/attack-of-the-week-group-messaging-in-whatsapp-and-signal/
- Schneier on Security: https://www.schneier.com/blog/archives/2018/01/whatsapp_vulner.html
- Bild: http://www.bild.de/digital/smartphone-und-tablet/whatsapp/whatsapp-sicherheitsluecke-in-gruppenchats-54452080.bild.html
- Sun: https://www.thesun.co.uk/tech/5316110/new-whatsapp-bug-how-to-stay-safe/

Related articles


miércoles, 10 de junio de 2020

5 Free Online Courses To Learn Artificial Intelligence

We are living in the era of fourth industrial revolution(4IR), where Artificial intelligence has a significant role to play. This 4IR technology embedded within societies and even into the human body. From Computer enthusiasts to common people, everyone should be aware and learn this breakthrough technology.
We think about gigantic Robots from Transformers when we hear about Artificial Intelligence(AI) which is a fiction in the past but a fact today, capable of transforming the whole tech world. The field of AI consists of more than Robots such as personal assistants, self-driving cars, apprenticeship learning, behavior cloning and so on. To learn about this advanced technology, thanks to the online learning resources which offers great content to get started with artificial intelligence.

Here are the 5 free e-learning courses on Artificial Intelligence

1. UC Berkeley CS188 Intro to AI

Get started with UC Berkeley AI course, this course is absolutely for beginners who are unaware of Artificial intelligence. It doesn't need any prior computer knowledge to know about AI. UC Berkeley allows anyone to learn this course for free. This course is systematically presented and consists of the following:
  • Course Schedule
  • Complete sets of Lecture Slides and Videos
  • Interface for Electronic Homework Assignments
  • Section Handouts
  • Specs for the Pacman Projects
  • Source files and PDFs of past Berkeley CS188 exams
  • Form to apply for edX hosted autograders for homework and projects (and more)
  • Contact information
Aside from this, you can also browse the following courses as well from UC Berkeley that are part of AI course:
  • Machine Learning: CS189, Stat154
  • Intro to Data Science: CS194-16
  • Probability: EE126, Stat134
  • Optimization: EE127
  • Cognitive Modeling: CogSci131
  • Machine Learning Theory: CS281A, CS281B
  • Vision: CS280
  • Robotics: CS287
  • Natural Language Processing: CS288

2. Artificial Intelligence: Principles and Techniques

This course is offered by Stanford with great content that includes topics, videos, assignments, projects, and exams. The whole course mainly focuses on the complex real-world problems and try to find similarity between web search, speech recognition, face recognition, machine translation, autonomous driving, and automatic scheduling. Here you will learn the foundational principles of AI and implement some the AI systems. The goal of this course is to help you tackle the real-world situations with the help of AI tools. So, it is the best for the beginner to get started with AI.

3. Learn with GOOGLE AI

Who will dislike the course from Google? absolutely no one. This company is one of the early adopters of AI has a lot to offer to learners. Learn with Google AI is an education platform for people at all experience levels, it is free to access and browse content. The education resources provided by Google is from the machine learning experts of the company. These resources are the collections of lessons, tutorials, and Hands-on exercises that help you start learning, building, and problem-solving.

4. MIT 6.S094: Deep Learning for Self-Driving Cars

This course gives the practical overview of Deep Learning and AI. It is the course for beginners, also for the people who are getting started with Machine Learning. The course also offers a lot of benefits to the experienced and advanced researchers in the field deep learning. This MIT's course takes people into the journey of Deep Learning with the applied theme of building Self-Driving cars. However, the course also offers slides and videos to engage the learners.

5. Fundamentals of Deep Learning for Computer Vision

This course is offered by Nvidia and Nvidia Deep learning Institute. Computer Vision is one of the disciplines of AI that acquire, analyze, process, and understand images. The course is completely free and everyone who is enthusiast about AI can access and learn the course. It is a hands-on course that able to provide basics of deep learning and deployment of neural networks. With this. you will also learn the following:
  • Identify the ingredients required to start a Deep Learning project.
  • Train a deep neural network to correctly classify images it has never seen before.
  • Deploy deep neural networks into applications.
  • Identify techniques for improving the performance of deep learning applications.
  • Assess the types of problems that are candidates for deep learning.
  • Modify neural networks to change their behavior.

More information


  1. Hacking Games
  2. Hacking For Dummies
  3. Pentest Questions
  4. Pentest Security
  5. Pentest Practice Sites
  6. Hacking Games Online
  7. Pentest Jobs
  8. Pentest Firewall
  9. Pentest Report Generator
  10. Pentest Process
  11. Hackerone
  12. Hacking Site
  13. Pentest Wifi
  14. Hacking Gif
  15. Pentest Gear
  16. Hacker Software
  17. Hacking Jacket
  18. Hacking Lab
  19. Pentest Meaning

Gridcoin - The Good

In this post we will take an in depth look at the cryptocurrency Gridcoin, we show how we found two critical design vulnerabilities and how we fixed them.

In the last past years we saw many scientific publications about cryptocurrencies. Some focused on theoretical parts [Source] and some on practical attacks against specific well-known cryptocurrencies, like Bitcoin [Source]. But in general there is a lack of practical research against alternative coins. Or did you know that there are currently over 830 currencies listed online? So we asked ourselves how secure are these currencies, and if they are not just re-branded forks of the Bitcoin source code?

Background

Gridcoin is an Altcoin, which is in active development since 2013. It claims to provide a high sustainability, as it has very low energy requirements in comparison to Bitcoin. It rewards users for contributing computation power to scientific projects, published on the BOINC project platform. Although Gridcoin is not as widespread as Bitcoin, its draft is very appealing as it attempts to eliminate Bitcoin's core problems. It possesses a market capitalization of $13,719,142 (2017/08/10).

Berkeley Open Infrastructure for Network Computing

To solve general scientific meaningful problems, Gridcoin draws on the well-known Berkeley Open Infrastructure for Network Computing (BOINC). It is a software platform for volunteer computing, initially released in 2002 and developed by the University of California, Berkeley. It is an open source software licensed under the GNU Lesser General Public License. The platform enables professionals in need for computation power to distribute their tasks to volunteers. Nowadays it is widely used by researchers with limited resources to solve scientific problems, for example, healing cancer, investigate global warming, finding extraterrestrial intelligence in radio signals and finding larger prime numbers.
When launching a BOINC project, its maintainer is required to set up his own BOINC server. Project volunteers may then create accounts (by submitting a username, a password and an email address) and work on specific project tasks, called workunits. The volunteers can process the project tasks and transfer their solutions with a BOINC client.

BOINC architecture

BOINC uses a client-server architecture to achieve its rich feature set. The server component handles the client requests for workunits and the problem solutions uploaded by the clients. The solutions are validated and assimilated by the server component. All workunits are created by the server component and each workunit represents a chunk of a scientific problem which is encapsulated into an application. This application consists of one or multiple in-/output files, containing binary or ASCII encoded parameters.

BOINC terminology

  • iCPID
    • The BOINC project server creates the internal Cross Project Identifier (iCPID) as a 16 byte long random value during account creation. This value is stored by the client and server. From this time on, the iCPID is included in every request and response between client and server
  • eCPID
    • The external Cross Project Identifier (eCPID) serves the purpose of identifying a volunteer across different BOINC projects without revealing the corresponding email address. It is computed by applying the cryptographic hash function MD5 to (iCPID,email) and thus has a length of 16 byte [Source].
eCPID = MD5(iCPID||email)
  • Credits
    • BOINC credits are generated whenever a host submits a solution to an assigned task. They are measured in Cobblestone, whereas one Cobblestone is equivalent to 1/200 of CPU time on a reference machine with 1,000 mega floating point operation per seconds [Source]
  • Total Credit
    • Total number of Cubblestones a user invested with his machines for scientific computations
  • Recent Average Credit (RAC)
    • RAC is defined as the average number of Cobblestones per day generated recently [Source]. If an entire week passes, the value is divided by two. Thus old credits are weakly weighted. It is recalculated whenever a host generates credit [Source].

Gridcoin

As a fork of Litecoin, Gridcoin-Research is a blockchain based cryptocurrency and shares many concepts with Bitcoin. While Bitcoin's transaction data structure and concept is used in an unmodified version, Gridcoin-Research utilizes a slightly modified block structure. A Gridcoin-Research block encapsulates a header and body. The header contains needed meta information and the body encloses transactions. Due to the hashPrevBlockHeader field, which contains the hash of the previous block-header, the blocks are linked and form the distributed ledger, the blockchain. Blocks in the blockchain are created by so called minters. Each block stores a list of recent transactions in its body and further metadata in its header. To ensure that all transactions are confirmed in a decisive order, each block-header field contains a reference to the previous one. To regulate the rate in which new blocks are appended to the blockchain and to reward BOINC contribution, Gridcoin-Research implements another concept called Proof-of-Research. Proof-of-Research is a combination of a new overhauled Proof-of-BOINC concept, which was originally designed for Gridcoin-Classic and the improved Proof-of-Stake concept, inspired by alternative cryptocurrencies.

Fig. 1: Gridcoin block structure

Gridcoin terminology

In order to understand the attacks we need to introduce some Gridcoin specific terms.
  • eCPID
    • Identifier value from BOINC used in Gridcoin to identify the researcher.
  • CPIDv2
    • contains a checksum to prove that the minter is the owner of the used eCPID. We fully describe the content of this field in the last attack section.
  • GRCAddress
    • contains the payment address of the minter.
  • ResearchAge
    • is defined as the time span between the creation time of the last Proof-of-Research generated block with the user's eCPID and the time stamp of the last block in the chain measured in days.
  • RSAWeight
    • estimates the user's Gridcoin gain for the next two weeks, based on the BOINC contribution of the past two weeks.

Proof-of-Stake

Proof-of-Stake is a Proof-of-Work replacement, which was first utilized by the cryptocurrency Peercoin in 2012. This alternative concept was developed to showcase a working Bitcoin related currency with low power consumption. Therefore, the block generation process has been overhauled. To create a new valid block for the Gridcoin blockchain the following inequality have to be satisfied:

SHA256(SHA256(kernel)) < Target * UTXO Value + RSAWeight

The kernel value represents the concatenation of the parameters listed in Table 2. The referenced unspent transaction output (UTXO) must be at least 16 hours old. The so called RSAWeight is an input value to the kernel computation, it's indicates the average BOINC work, done by a Gridcoin minter.
In direct comparison to Bitcoin's Proof-of-Work concept, it is notable that the hash of the previous block-header is not part of the kernel. Consequently, it is theoretically possible to create a block at any previous point in time in the past. To prevent this, Gridcoin-Research creates fixed interval checkpoint blocks. Once a checkpoint block is synchronized with the network, blocks with older time stamps became invalid. Considering the nature of the used kernel fields, a client with only one UTXO is able to perform a hash calculation each time nTime is updated. This occurs every second, as nTime is a UNIX time stamp. To be able to change the txPrev fields and thereby increase his hash rate, he needs to gain more UTXO by purchasing coins. Note that high UTXO and RSAWeight values mitigate the difficulty of the cryptographic puzzle, which increase the chance of finding a valid kernel. RSAWeight was explained above. Once a sufficient kernel has been found, the referenced UTXO is spent in a transaction to the creator of the block and included in the generated block. This consumes the old UTXO and generates a new one with the age of zero.

The Gridcoin-Research concept does not require much electrical power, because the maximum hash rate of an entity is limited by its owned amount of UTXOs with suitable age.

Proof-of-Research

Minters relying solely on the Proof-of-Stake rewards are called Investors. In addition to Proof-of-Stake, Gridcoin gives minters a possibility to increase their income with Proof-of-Research rewards. The Proof-of-Research concept implemented in Gridcoin-Research allows the minters to highly increase their block reward by utilizing their BOINC Credits. In this case the minter is called a Researcher.
To reward BOINC contribution, relevant BOINC data needs to be stored in each minted block. Therefore, the software uses the BOINCHash data structure, which is encapsulated in the first transaction of each block. The structure encloses the fields listed in Table 6. The minting and verification process is shown in Figure 2 and works as follows:
  1. A minter (Researcher) participates in a BOINC project A and performs computational work for it. In return the project server increases the users Total Credit value on the server. The server therefore stores the minter's email address, iCPID, eCPID and RAC.
  2. Statistical websites contact project server and down-load the statistics for all users from the project server (A).
  3. After the user earns credits, his RAC increases. Consequently, this eases the finding of a solution for the Proof-of-Stake cryptographic puzzle, and the user can create (mint) a block and broadcast it to the Gridcoin network.
  4. Another minter (Investor or Researcher) will receive the block and validate it. Therefore, he extracts the values from the BOINCHash data structure inside the block.
  5. The minter uses the eCPID from the BOINCHash to request the RAC and other needed values from a statistical website and compares them to the data extracted from the BOINCHash structure, in the event that they are equal and the block solves the cryptographic puzzle, the block is accepted.

 Fig. 2: Gridcoin architecture and minting process

Reward calculation

The total reward for a solved block is called the Subsidy and is computed as the sum of the Proof-of-Research and the Proof-of-Stake reward.
If a minter operates as an Investor (without BOINC contribution), the eCPID is set to the string Investor and all other fields of the BOINCHash are zeroed. An Investor receives only a relatively small Proof-of-Stake reward.
Because the Proof-of-Research reward is much higher than its Proof-of-Stake counterpart, contributing to BOINC projects is more worth the effort.

Statistic Website

At the beginning of the blog post, the core concept behind BOINC was described. One functionality is the creation of BOINC Credits for users, who perform computational work for the project server. This increases the competition between BOINC users and therefore has a positive effect on the amount of computational work users commit. Different websites 4 collect credit information of BOINC users from known project servers and present them online. The Gridcoin client compares the RAC and total credit values stored in a new minted block with the values stored on cpid.gridcoin.us:5000/get_user.php?cpid=eCPID where eCPID is the actual value of the researcher. If there are differences, the client declines the block. In short, statistical websites are used as control instance for Gridcoin. It is obvious that gridcoin.us administrators are able to modify values of any user. Thus, they are able to manipulate the amount of Gridcoins a minter gets for his computational work. This is crucial for the trust level and undermines the general decentralized structure of a cryptocurrency.

Project Servers

Gridcoin utilizes BOINC projects to outsource meaningful computation tasks from the currency. For many known meaningful problems there exist project servers 5 that validate solutions submitted by users, 6 and decide how many credits the users receive for their solutions. Therefore, the project servers can indirectly control the amount of Gridcoins a minter gets for his minted block via the total credit value. As a result, a Gridcoin user also needs to trust the project administrators. This is very critical since there is no transparency in the credit system of project server. If you want to know why decentralization is not yet an option, see our paper from WOOT'17.

Attacks

In addition to the trust a Gridcoin user needs to put into the project server and statistic website administrators, Gridcoin suffers from serious flaws which allows the revelation of minter identities or even stealing coins. Our attacks do not rely on the Gridcoin trust issues and the attacker does not need to be in possession of specific server administrative rights. We assume the following two simple attackers with limited capability sets. The first one, is the blockchain grabber which can download the Gridcoin blockchain from an Internet resource and runs a program on the downloaded data. The second one, the Gridcoin attacker, acts as a normal Gridcoin user, but uses a modified Gridcoin client version, in order to run our attacks.

Interestingly, the developer of Gridcoin tried to make the source code analysis somewhat harder, by obfuscating the source code of relevant functions.
 Fig. 3: Obfuscated source code in Gridcoin [Source]

Grab Gridcoin user email addresses

In order to protect the email addresses of Gridcoin Researchers, neither BOINC project websites nor statistical websites directly include these privacy critical data. The statistical websites only include eCPID entries, which are used to reward Gridcoin Researchers. However, the email addresses are hidden inside the computation of the BOINCHash (cf. Table 1). A BOINCHash is created every time a Researcher mints a new block and includes a CPIDv2 value. The CPIDv2 value contains an obfuscated email address with iCPID and a hash over the previous blockchain block.
By collecting the blockchain data and reversing the obfuscation function (cf. Figure 4 and Figure 7), the attacker gets all email addresses and iCPIDs ever used by Gridcoin Researchers. See the reversed obfuscation function in Figure 4 and Figure 5.

Evaluation

We implemented a deobfuscation function (cf. Figure 7) and executed it on the blockchain. This way, we were able to retrieve all (2709) BOINC email addresses and iCPIDs used by Gridcoin Researchers. This is a serious privacy issue and we address it with our fix (cf. The Fix).

Steal Gridcoin users BOINC reward

The previous attack through deobfuscation allows us to retrieve iCPID values and email addresses. Thus, we have all values needed to create a new legitimate eCPID. This is required because the CPIDv2 contains the last block hash and requires a re-computation for every new block it should be used in. We use this fact in the following attack and show how to steal the computational work from another legitimate Gridcoin Researcher by mining a new Gridcoin block with forged BOINC information. Throughout this last part of the post, we assume the Gridcoin Minter attacker model where the attacker has a valid Gridcoin account and can create new blocks. However, the attacker does not perform any BOINC work.

 Tab. 1: BOINCHash structure as stored and used in the Gridcoin blockchain.
As stated at the beginning of the blog post, the pre-image of the eCPID is stored obfuscated in every Gridcoin block, which contains a Proof-of-Research reward. We gathered one pre-image from the minted blocks of our victim and deobfuscated it. Thus, we know the values of the iCPID, and the email address of our victim. Subsequently, use the hash of the last block created by the network and use these three values to create a valid CPIDv2. Afterwards we constructed a new block. In the block we also store the current BOINC values of our victim, which we can gather from the statistics websites. The final block is afterwards sent into the Gridcoin network. In case all values are computed correctly by the attacker, the network will accept the block, and resulting in a higher reward for the attacker, consisting of Proof-of-Stake and Proof-of-Research reward.



 Fig. 4: Obfuscation function  Fig. 5: Deobfuscation function

Evaluation

In order to verify our attacks practically, we created two virtual machines (R and A), both running Ubuntu 14.04.3 LTS. The virtual machine R contained a legitimate BOINC and Gridcoin instance. It represented the setup of a normal Gridcoin Researcher. The second machine A contained a modified Gridcoin-Research client 3.5.6.8 version, which tried to steal the Proof-of-Research reward of virtual machine R. Thus, we did not steal reward of other legitimate users. The victim BOINC client was attached to the SETI@home project 11 with the eCPID 9f502770e61fc03d23d8e51adf7c6291.
The victim and the attacker were in possession of Gridcoins, enabling them to stake currency and to create new blocks.
 Fig. 6: CPIDv2 calculation deobfuscated

Initially both Gridcoin-Research clients retrieved the blockchain from other Gridcoin nodes in the Gridcoin network.
The Gridcoin attack client made it possible to specify the victim email address, iCPID and target project. All these values can be retrieved from the downloaded blockchain and our previous attack via the reverseCPIDv2 function as shown in Figure 7. The attack client read the iCPID and email address of the victim from a modified configuration file. All other values, for example, RAC or ResearchAge, were pulled from http://cpid.gridcoin.us:5000/get_user.php?cpid=. As soon as all values were received, the client attempted to create a new valid block.


 Fig. 7: Reverse the CPIDv2 calculation to get iCPID and email address

Once a block had been created and confirmed, the attacker received the increased coin reward with zero BOINC contribution done. The attack could only be detected by its victims because an outside user did not know the legitimate Gridcoin addresses a Researcher uses.
All blocks created with our victim's eCPID are shown in Table 2. Illegitimate blocks are highlighted. We were able to mint multiple illegitimate blocks, and thus stealing Research Age from our victim machine R. All nine blocks created and send by our attacker to the Gridcoin network passed the Gridcoin block verification, were confirmed multiple times, and are part of the current Gridcoin blockchain. During our testing timespan of approximately three weeks, the attacker machine was wrongfully rewarded with 72.4 Proof-of-Research generated Gridcoins, without any BOINC work. The results show that the attack is not only theoretically possible, but also very practical, feasible and effective. The attack results can be reproduced with our Gridcoin-Research-Attack client.

 Tab. 2:Blocks minted with the victim's eCPID

The Fix

In order to fix the security issue, we found one solution which does not require any changes to the BOINC source code nor the infrastructure. It is sufficient to change some parts of the already existing Gridcoin Beacon system. Thus, our solution is backwards compatible.
The current Gridcoin client utilizes so called Beacons to register new eCPIDs and stores them as a transaction of 0.0001 Gridcoins in a Superblock which is created every 24 hours. A Beacon encloses the user's personal eCPIDs, a corresponding unused (but irreversible) CPIDv2, and the wallet's main Gridcoin payment address. Once the Superblock is created, the eCPIDs is bound to one Gridcoin payment address. During the block verification process this bond is unfortunately not checked. Furthermore, the existing Beacon system does not use any strong asymmetric cryptography to ensure authenticity and integrity of the broadcasted data. We propose to extend the Beacon system with public key cryptography. In detail, we suggest that a user binds his fresh public key PK_1 to a newly generated eCPID, and then storing them together in a Superblock. An initial Beacon would therefore contain a hashed (e.g. SHA-256) eCPID, the public key, a Nonce, and a cryptographic signature created with the corresponding secret key SK_1 of the public key. This allows only the owner of the secret key to create valid signatures over blocks created with his eCPID. Thus, an adversary first needs to forge a cryptographic signature before he can claim Proof-of-Research work of another Gridcoin user. Thus, he is not capable of stealing the reward of the user.

Beacon to create a eCPID, public/secret key pair bond

For verification purposes nodes fetch the corresponding latest public key from one of the Superblocks. Furthermore, this Beacon structure allows a user to replace his previous public key associated with his eCPID. This is realized by submitting a new Beacon with a new public key PK_2, signed with his old secret key.

Beacon to update a eCPID, public/secret key pair bond

All Beacons in the chain are verifiable and the latest public key is always authentic. The Nonce provide freshness for the signature input, and therefore prevent replay attacks against the Beacon system.
Note that the eCPID needs to be completely unknown to the network, when sending the initial Beacon, for this concept to work as intended. The hash function ensures, that the Beacon does not reveal the fresh eCPID. As a result, an attacker is unable to mint with a eCPID even if he was able to intercept an initial Beacon and replaced the public key and signature with his own parameters, beforehand. This solution does not require any changes in the BOINC source code or the project servers.

Sign a block

In order to claim the Proof-of-Research reward for a newly created block, the Gridcoin minter computes a signature over the hash of the blockheader. Afterwards, he stores the resulting value at the end of the corresponding block in a new field. The private key used for the signature generation must correspond to the advertised public key by the user. It is important to note that the signature value is not part of the Merkle tree, and thus does not change the blockheader. In the end, the signature can then be verified by every other Gridcoin user via the advertised public key corresponding to the eCPID of the Gridcoin minter.

Responsible Disclosure

The attacks and the countermeasures were responsibly disclosed to the Gridcoin developer on the 14th of September, 2016. The developer used our proposed countermeasures and started to implement a new version. Since version 3.5.8.8, which is mandatory for all Gridcoin users, there exists an implementation, which contains countermeasures to our reward stealing attack.
See our next blog post, why Gridcoin is still insecure and should not be used anymore.

Further Reading
A more detailed description of Gridcoin and the attacks will be presented at WOOT'17, the paper is available here.

Authors

Tobias Niemann
Juraj Somorovsky
Read more
  1. Pentesting
  2. Hacking Google
  3. Pentest Partners
  4. Basic Pentest 1 Walkthrough
  5. Pentest Lab Setup
  6. Pentest Devices
  7. Hacking Software
  8. Hacker Google
  9. Pentest Documentation
  10. Pentest Lab Setup

Change Passwords Regularly - A Myth And A Lie, Don'T Be Fooled, Part 2

In the previous blog post, I have covered the different passwords you have to protect, the attackers and attack methods. Now let's look at how we want to solve the issue.

Password requirements

So far we have learned we have to use long, complex, true random passwords. In theory, this is easy.
Now, this is my password advice for 2014:

Password character classes
Use upper-lower-digit-special characters in general cases.
If you don't understand what I just write, choose from this:
qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM0123456789-=[];'\,./<>?:"|{}_+!@#$%^&* ()`~
If you are a CISO, and say: use 3 out of 4 character class, everyone will use Password12 or Welcome12 as their password (after the 12th enforced password change).

Password length
This is basically the only thing which changes whether the password is in the very high/high/medium/low level. Check the previous blog post for the details about very high/high/medium/low level.

Password length: Very high level class (including work-related/enterprise passwords)
15 character (or 20 if you are really paranoid). Making true random passwords longer than 20 characters usually does not make any sense, even in high security scenarios (e.g. military, spy agencies, etc.). 15 character in Windows environment is a right choice, as LM hash is incompatible with 15 character passwords, thus one (effective) attack won't work. Beware, there might be bugs with using 15 character passwords, with a low probability.

Password length: High-level class
12 character, upper-lower-special characters

Password length: Medium class
10 character, upper-lower-special characters, still TRUE random

Password length: Low-level class
9 character. Why less?

Pin codes
Always choose the longest provided, but a maximum of 8. Usually, more is pretty impractical.

Password randomness
True random, generated by a (local) computer. Avoid Debian. Avoid random generated by your brain. Do not use l33tsp33k. Do not append or prepend the current month, season or year to a word. Do not use Star Wars/Star Trek/(your favorite movie/series here) characters or terminology. In general, avoid any pattern like the above ones. The chances that a true random password generator generates SkyWalker12 is very-very low. And believe me, it is not that hard to crack those. Every algorithm that you would come up with; the bad guys have already thought of it. Use true random. Let the computer do it for you. See details later in this post.

Password history
Never-ever reuse passwords. NEVER!

Password change period
If it is not enforced otherwise, don't bother to change it twice in a year. But! Check if the password cracking speed made your current ones obsolete. If yes, change the obsolete passwords. Immediately change the password if you have been notified that the service you use has been compromised. Immediately change all of your recently used passwords if you suspect malware was running on your computer (do this on a known clean computer). Immediately change your password if you have used it on a computer you don't own, or there is a small chance malware is running on it. Change it if you really had to give your password to someone. Otherwise, goodbye regular password change. We will miss you...

If you are a CISO, and writing security policies, you should have to enforce the password change period based on: do you allow LM hashes? What is the password length requirement for users and administrators? What is the current hash cracking speed, and the forecast for the next 2 years? I think people would be happy to increase their passwords with 1-2 characters, if they are not forced to change it frequently (e.g. every month).
Now after I was sooo smart giving advises people still hate to implement, let's see the practical implementations. At least some people might like me, because I told them not to change the passwords regularly. Next time someone tells you to change all your important passwords regularly, put a lie detector on him, and check if he changes all of his passwords regularly. If he lies, feel free to use the wrench algorithm to crack his passwords. If he was not lying, call 911, to put a straitjacket on him. Only insane paranoid people do that in reality. Others are just too scared to say "what everyone recommended so far is bullshit". Comments are welcome ;) Other people might hate me for telling them using true random passwords. Don't panic, keep reading.
And don't forget to use 2 factor authentication. It might seem a bit of an overkill at the beginning, but after months, you won't notice using it.

(Bad and good) solutions

I will use the same password everywhere

This is a pretty bad idea. If one of the passwords are compromised, either the attackers can access your other sites, or you have to change all of your passwords. There are better ways to spend your life on earth than changing all of your passwords.

I will remember it

Good luck remembering 250 different, complex passwords. Don't forget to change them regularly! ;)

I will use the password recovery all the time

Not a very user-friendly solution. And because the security answer has to be as complicated as the password itself, the problem has not been solved.

I will write it down into my super-secret notebook and put it in my drawer

Although it might work in some cases, it won't work in others. I don't recommend it.





I will use an algorithm, like a base password, and add the websites first letters to the end of the password

Still better than using the same password everywhere, but believe me, if this is a targeted attack, it is not that hard to guess your password generation algorithm.

I will use the advice from XKCD, and use the password correcthorsebatterystaple

Still a lot better than simple passwords, but unfortunately, people are still bad at choosing random words with random order, so it is not the best solution. And again, you can't memorize 250 different passwords ... Even 10 is impossible. Only use this method in special corner cases (see details later), and use a passphrase generator!

I will use a password manager

This is the very first good idea. It solves the problem of remembering 250 different complex and random passwords. Some people might complain about using a password manager, here are those complaints. And my answers:

If someone gets access to this one password store, all is lost.
Answer: If someone accessed your password store, and the master password, you can be pretty damn sure that most of your passwords are already stolen. For extra paranoids, you can use multiple password stores, one for daily use, one for rare cases. Beware not to forget the password for the second one ;)

What if I don't have access to the password store when I need it?
Answer: In the age of cheap notebooks, tablets, and smartphones, in 99% of the cases you should not use that important password on any other device than yours. In the rare cases when you must, you can use either your smartphone to get the password, or use a browser extension like Password hasher to generate different passwords to different websites, with one password. For extra paranoids, you can have different master passwords for the different security levels. And don't forget to change the password after you are back at your own computer.

What if I forgot the one password to the password store?
Answer: If you use your password manager daily, it has the same odds to forget that one password as it is to forget every one of your passwords.

Password managers make phishing attacks easier.
Answer: Who started this nonsense? Good password managers decrease the risk of phishing.

Password managers have the same vulnerabilities as other websites or software.
Answer: Well, this is partially true. There are at least 3 types of password managers, from most secure to least: offline, browser built-in, online. Online password managers give better user experience, with a sacrifice in security. But if you choose one of the leading password managers, and you are a simple home user, the risks are negligible. If you try to store your work password in an online password store, you might violate your internal security policy. For paranoids, use offline password managers, and back them up regularly. If you choose an online password manager, at least use 2-factor authentication. And don't forget, your Chrome password can be easily synchronized to the cloud, shifting it to the online category.

In some cases, like Full Disc Encryption, OS login, smartphone login, or password manager login, the auto-type of password from the password manager is not available, thus choosing a true random password is a pain in the a$$.
Answer: True. Generate pronounceable passwords or passphrases in these corner cases, e.g. with the Linux tool apg you can generate pronounceable passwords. For easy and fast type, don't use capital letters (only lower-alpha - digit - special) in the original password, but increase the length of the password. Add 1 extra character because you don't use upper case letters, add 3 other because it is a pronounceable password, and you are good to go. For extra paranoids change one or two of the letters to uppercase where it is convenient. 
apg -M SNL -m 15 is your friend.
If you want to check what I write here (always a good idea), test the entropy of a true random 10 character password with all character classes, and check it with 14 characters, without uppercase. I recommend KeePass for that. If you comment on this that "Keepass can not measure that it is a pronounceable password, thus the entropy is lower in reality", my answer is: "Check out the current passwords used by users, and current password advises, and tell me if this password is a lot better or not ..." . You have been warned.
 

For the high-level password class, I don't recommend anything your brain generated. There are also suitable offline passphrase generators. Use at least 5-6 words for passphrases.

Password managers are not user-friendly, it takes more time to log in.
Answer: If you set auto-type/auto-fill, and the password manager is opened once a day (and you lock your computer when you leave it), in this case, logging in takes less time than typing it! It is more convenient to use it, rather than typing the passwords every time.

I like to create new unique passwords every time I create a new account, and password managers take the fun away from it.
Answer: Said no one, ever! "38 percent of people think it sounds more appealing to tackle household chores – from folding the laundry to scrubbing toilets – than to try and come up with another new user name or password."

To summarize things. Use a password manager.

General advise

Never use your essential passwords on other computers. They might be infected with a password stealer. If you really have to use it, change the password as soon as possible on a trusted (your) computer.

Don't fool yourself by phishing sites. If you go to the local flea market, and there is a strange looking guy with "Superbank deposit here" logo above his head, will you put your money?

Protect yourself against malware. Use a recent operating system, and even if you use OSX or Linux, it is not a bad thing to have an AV as a "last line of defense". Or to check your pendrive for Windows USB worms.

Never-ever use online web sites to "generate your password", "measure the complexity of your password" or "check if it has been breached". Never! (Except if it is your password manager :) ... )

Update: Sign up on the https://haveibeenpwned.com/ for notification if your e-mail is found in a leak.

Changing passwords frequently is bad advice. It is not effective. Put more energy in other right password advise. 

Related news


  1. Hacker Computer
  2. Hacking Games Online
  3. Hacker Box
  4. Hacking Script
  5. Pentest Vpn
  6. Pentest With Kali Linux
  7. Hacking Lab
  8. Pentest As A Service
  9. Pentestgeek
  10. Hacking Tools
  11. Pentest Book
  12. Pentest Stages
  13. Hacking Language
  14. Pentest Jobs
  15. Hacking Simulator
  16. How To Pentest A Website
  17. Hacker Forum
  18. Hacker Code
  19. Hacking Groups