Tony'sCapsule: 五月 2023

2023年5月31日星期三

DSniff

"dsniff is a collection of tools for network auditing and penetration testing. dsniff, filesnarf, mailsnarf, msgsnarf, urlsnarf, and webspy passively monitor a network for interesting data (passwords, e-mail, files, etc.). arpspoof, dnsspoof, and macof facilitate the interception of network traffic normally unavailable to an attacker (e.g, due to layer-2 switching). sshmitm and webmitm implement active monkey-in-the-middle attacks against redirected SSH and HTTPS sessions by exploiting weak bindings in ad-hoc PKI." read more...

Website: http://www.monkey.org/~dugsong/dsniff/

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Stop Using MD-5, Now!

TL;DR: Don't use MD-5 to identify malware samples. Believe me, it is a bad idea. Use SHA-256 or a stronger hash function.

This post is dedicated to all malware researchers, still using MD-5 to identify malware samples.

Before deep-diving into the details, let me explain my view on this topic. Whenever you want to identify a malware, it is only OK to publish the MD-5 hash of the malware if you post at least the SHA-256 hash of the malware as well. Publishing only the MD-5 hash is unprofessional. If you want to understand why, please continue reading. If you know about the problem, but want to help me spread the word, please link to my site www.stopusingmd5now.com.

By writing articles/posts/etc. and publishing the MD-5 hash only, it is the lesser problem that you show people your incompetency about hash functions, but you also teach other people to use MD-5. And it spreads like a disease... Last but not least, if I find a sample on your blog post, and you use MD-5 only, I can't be sure we have the same sample.

Here is a list to name a few bad examples (order is in Google search rank order):

Kaspersky
Bromium
Fireeye
Webroot
Mcafee
Fox-IT
Cisco
SANS
ESET
Symantec
Watchguard
And unfortunately, even the best books on malware analysis promote the use of MD-5 - see "Practical malware analysis" Chapter 1 Page 10

Introduction to (cryptographic) hash functions

A long time ago (according to some sources since 1970) people started designing hash functions, for an awful lot of different reasons. It can be used for file integrity verification, password verification, pseudo-random generation, etc. But one of the most important properties of a cryptographic hash function is that it can "uniquely" identify a block of data with a small, fixed bit string. E.g., malware can be identified by using only the hash itself, so everybody who has the same malware sample will have the same hash; thus they can refer to the malware by the hash itself.

It is easy to conclude that there will always be collisions, where a different block of data has the same result hashes. The domain (block of data) is infinite, while the codomain (possible hash values) is finite. The question is how easy it is to find two different blocks of data, having the same hash. Mathematicians call this property "collision resistance." Proper cryptographic hash functions are collision-resistant, meaning it is impractical or impossible to find two different blocks of data, which have the same hash.

In 1989 Ronald Rivest (the first letter in the abbreviation of the RSA algorithm) designed the MD-2 hashing algorithm. Since 1997 there are publications about that this hashing algorithm is far from perfect.

In 1990 Ronald Rivest designed the MD-4 algorithm, which is considered as broken at least from 1991. But MD-4 is still in use from Windows XP until Windows 8 in the password protocol (NTLM). Unfortunately, there are more significant problems with NTLM besides using MD-4, but this can be the topic of a different blog post.

In 1991 (you might guess who) designed yet another hashing algorithm called MD-5, to replace MD-4 (because of the known weaknesses). But again, in from 1993 it has been shown many times that MD-5 is broken as well. According to Wikipedia, "On 18 March 2006, Klima published an algorithm [17] that can find a collision within one minute on a single notebook computer, using a method he calls tunneling". This means, that with the 8 years old computing power of a single notebook one can create two different files having the same MD-5 hash. But the algorithms to generate collisions have been improved since, and "a 2013 attack by Xie Tao, Fanbao Liu, and Dengguo Feng breaks MD-5 collision resistance in 2^18 time. This attack runs in less than a second on a regular computer." The key takeaway here is that it is pretty damn hard to design a secure cryptographic hash function, which is fast, but still safe. I bet that if I would develop a hash function, Ron would be able to hack it in minutes.

Now, dear malware researcher, consider the following scenario. You as, a malware analyst, find a new binary sample. You calculate the MD-5 hash of the malware, and Google for that hash. You see this hash value on other malware researchers or on a sandbox/vendor's site. This site concludes that this sample does this or that, and is either malicious or not. Either because the site is also relying solely on MD-5 or because you have only checked the MD-5 and the researcher or sandbox has a good reputation, you move on and forget this binary. But in reality, it is possible that your binary is totally different than the one analyzed by others. The results of this mistake can scale from nothing to catastrophic.

If you don't believe me, just check the hello.exe and erase.exe on this site from Peter Sellinger. Same MD-5, different binaries; a harmless and a (fake) malicious one... And you can do the same easily at home. No supercomputers, no NSA magic needed.

On a side-note, it is important to mention that even today it can be hard to find a block of data (in generic), if only the MD-5 hash is known ("pre image resistance"). I have heard people arguing this when I told them using MD-5 as a password hash function is a bad idea. The main problem with MD-5 as a password hash is not the weaknesses in MD-5 itself, but the lack of salt, lack of iterations, and lack of memory hardness. But still, I don't see any reason why you should use MD-5 as a building block for anything, which has anything to do with security. Would you use a car to drive your children to the school, which car has not been maintained in the last 23 year? If your answer is yes, you should neither have children nor a job in IT SEC.

Conclusion

If you are a malware researcher, and used MD-5 only to identify malware samples in the past, I suggest to write it down 1000 times: "I promise I won't use MD-5 to identify malware in the future."

I even made a website dedicated to this problem, www.stopusingmd5now.com . The next time you see a post/article/whatever where malware is identified by the MD-5 hash only, please link to this blog post or website, and the world will be a better and more professional place.

PS: If you are a forensics investigator, or software developer developing software used in forensics, the same applies to you.
PS 2: If you find this post too provocative and harsh, there is a reason for this ...

Update: I have modified two malware (Citadel, Atrax) with the help of HashClash, and now those have the same MD-5. Many thanks for Marc Stevens for his research, publishing his code, and help given during the collision finding.

2023年5月30日星期二

The OWASP Foundation Has Selected The Technical Writer For Google Season Of Docs

The OWASP Foundation has selected the technical writer for Google Season of Docs by Fabio Cerullo

The OWASP Foundation has been accepted as the organization for the Google Seasons of Docs, a project whose goals are to give technical writers an opportunity to gain experience in contributing to open source projects and to give open-source projects an opportunity to engage the technical writing community.

During the program, technical writers spend a few months working closely with an open-source community. They bring their technical writing expertise to the project's documentation, and at the same time learn about open source and new technologies.

The open-source projects work with the technical writers to improve the project's documentation and processes. Together they may choose to build a new documentation set, or redesign the existing docs, or improve and document the open-source community's contribution procedures and onboarding experience. Together, we raise public awareness of open source docs, of technical writing, and of how we can work together to the benefit of the global open source community.

After a careful review and selection process, the OWASP Foundation has picked the primary technical writer who will work along the OWASP ZAP Team for the next 3 months to create the API documentation of this flagship project.

Congratulations to Nirojan Selvanathan!

Please refer to the linked document where you could look at the deliverables and work execution plan.

https://drive.google.com/open?id=1kwxAzaqSuvWhis9Xn1VKNJTJZPM2UV20

OVER $60 MILLION WORTH OF BITCOINS HACKED FROM NICEHASH EXCHANGE

Over $60 Million Worth of Bitcoins Hacked from NiceHash Exchange. Bitcoin mining platform and exchange NiceHash has been hacked, leaving investors short of close to $68 million in BTC.

As the price of Bitcoin continues to rocket, surging past the $14,500 mark at the time of writing, cyberattackers have once again begun hunting for a fresh target to cash in on in this lucrative industry.

Banks and financial institutions have long cautioned that the volatility of Bitcoin and other cryptocurrency makes it a risky investment, but for successful attackers, the industry potentially provides a quick method to get rich — much to the frustration of investors.

Unfortunately, it seems that one such criminal has gone down this path, compromising NiceHash servers and clearing the company out.

In a press release posted on Reddit, on Wednesday, NiceHash said that all operations will stop for the next 24 hours after their "payment system was compromised and the contents of the NiceHash Bitcoin wallet have been stolen."

NiceHash said it was working to "verify" the precise amount of BTC stolen, but according to a wallet which allegedly belongs to the attacker — traceable through the blockchain — 4,736.42 BTC was stolen, which at current pricing equates to $67,867,781.

"Clearly, this is a matter of deep concern and we are working hard to rectify the matter in the coming days," NiceHash says. "In addition to undertaking our own investigation, the incident has been reported to the relevant authorities and law enforcement and we are co-operating with them as a matter of urgency."

"We are fully committed to restoring the NiceHash service with the highest security measures at the earliest opportunity," the trading platform added.

The company has also asked users to change their online passwords as a precaution. NiceHash says the "full scope" of the incident is unknown.

"We are truly sorry for any inconvenience that this may have caused and are committing every resource towards solving this issue as soon as possible," the company added.

Inconvenience is an understatement — especially as so much was left in a single wallet — but the moment those coins shift, we may know more about the fate of the stolen investor funds.

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