domingo, 19 de abril de 2020

New Printers Vulnerable To Old Languages

When we published our research on network printer security at the beginning of the year, one major point of criticism was that the tested printers models had been quite old. This is a legitimate argument. Most of the evaluated devices had been in use at our university for years and one may raise the question if new printers share the same weaknesses.

35 year old bugs features

The key point here is that we exploited PostScript and PJL interpreters. Both printer languages are ancient, de-facto standards and still supported by almost any laser printer out there. And as it seems, they are not going to disappear anytime soon. Recently, we got the chance to test a $2,799 HP PageWide Color Flow MFP 586 brand-new high-end printer. Like its various predecessors, the device was vulnerable to the following attacks:
  • Capture print jobs of other users if they used PostScript as a printer driver; This is done by first infecting the device with PostScript code
  • Manipulate printouts of other users (overlay graphics, introduce misspellings, etc.) by infecting the device with PostScript malware
  • List, read from and write to files on the printers file system with PostScript as well as PJL functions; limited to certain directories
  • Recover passwords for PostScript and PJL credentials; This is not an attack per se but the implementation makes brute-force rather easy
  • Launch denial of Service attacks of various kinds:

Now exploitable from the web

All attacks can be carried out by anyone who can print, which includes:
Note that the product was tested in the default configuration. To be fair, one has to say that the HP PageWide Color Flow MFP 586 allows strong, Kerberos based user authentication. The permission to print, and therefore to attack the device, can be be limited to certain employees, if configured correctly. The attacks can be easily reproduced using our PRET software. We informed HP's Software Security Response Team (SSRT) in February.

Conclusion: Christian Slater is right

PostScript and PJL based security weaknesses have been present in laser printers for decades. Both languages make no clear distinction between page description and printer control functionality. Using the very same channel for data (to be printed) and code (to control the device) makes printers insecure by design. Manufacturers however are hard to blame. When the languages were invented, printers used to be connected to a computer's parallel or serial port. No one probably thought about taking over a printer from the web (actually the WWW did not even exist, when PostScript was invented back in 1982). So, what to do? Cutting support for established and reliable languages like PostScript from one day to the next would break compatibility with existing printer drivers. As long as we have legacy languages, we need workarounds to mitigate the risks. Otherwise, "The Wolf" like scenarios can get very real in your office…

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TLS-Attacker V2.2 And The ROBOT Attack

We found out that many TLS implementations are still vulnerable to different variations of a 19-year old Bleichenbacher's attack. Since Hanno argued to have an attack name, we called it ROBOT: https://robotattack.org

Given the new attack variants, we released a new version of TLS-Attacker 2.2, which covers our vulnerabilities.

Bleichenbacher's attack from 1998

In 1998, Daniel Bleichenbacher discovered that the error messages given by SSL servers for errors in the PKCS #1 1.5 padding allow an adversary to execute an adaptive-chosen ciphertext attack. This attack also belongs to the category of padding oracle attacks. By performing the attack, the adversary exploits different responses returned by the server that decrypts the requests and validates the PKCS#1 1.5 padding. Given such a server, the attacker can use it as an oracle and decrypt ciphertexts.
We refer to one of our previous blog posts for more details.

OK, so what is new in our research?

In our research we performed scans of several well-known hosts and found out many of them are vulnerable to different forms of the attack. In the original paper, an oracle was constructed from a server that responded with different TLS alert messages. In 2014, further side-channels like timings were exploited. However, all the previous studies have considered mostly open source implementations. Only a few vulnerabilities have been found.

In our scans we could identify more than seven vulnerable products and open source software implementations, including F5, Radware, Cisco, Erlang, Bouncy Castle, or WolfSSL. We identified new side-channels triggered by incomplete protocol flows or TCP socket states.

For example, some F5 products would respond to a malformed ciphertext located in the ClientKeyExchange message with a TLS alert 40 (handshake failure) but allow connections to timeout if the decryption was successful. We could observe this behaviour only when sending incomplete TLS handshakes missing ChangeCipherSpec and Finished messages.
See our paper for more interesting results.

Release of TLS-Attacker 2.2

These new findings motivated us to implement the complete detection of Bleichenbacher attacks in our TLS-Attacker. Before our research, TLS-Attacker had implemented a basic Bleichenbacher attack evaluation with full TLS protocol flows. We extended this evaluation with shortened protocol flows with missing ChangeCipherSpec and Finished messages, and implemented an oracle detection based on TCP timeouts and duplicated TLS alerts. In addition, Robert (@ic0ns) added many fixes and merged features like replay attacks on 0-RTT in TLS 1.3.
You can find the newest version release here: https://github.com/RUB-NDS/TLS-Attacker/releases/tag/v2.2

TLS-Attacker allows you to automatically send differently formatted PKCS#1 encrypted messages and observe the server behavior:
$ java -jar Attacks.jar bleichenbacher -connect [host]:[port]
In case the server responds with different error messages, it is most likely vulnerable. The following example provides an example of a vulnerable server detection output:
14:12:42 [main] CONSOLE attacks.impl.Attacker - A server is considered vulnerable to this attack if it responds differently to the test vectors.
14:12:42 [main] CONSOLE attacks.impl.Attacker - A server is considered secure if it always responds the same way.
14:12:49 [main] CONSOLE attacks.impl.Attacker - Found a difference in responses in the Complete TLS protocol flow with CCS and Finished messages.
14:12:49 [main] CONSOLE attacks.impl.Attacker - The server seems to respond with different record contents.
14:12:49 [main] INFO  attacks.Main - Vulnerable:true
In this case TLS-Attacker identified that sending different PKCS#1 messages results in different server responses (the record contents are different).

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Ransomware.OSX.KeRanger Samples


Research: New OS X Ransomware KeRanger Infected Transmission BitTorrent Client Installer by Claud Xiao

Sample credit: Claud Xiao


File information

d1ac55a4e610380f0ab239fcc1c5f5a42722e8ee1554cba8074bbae4a5f6dbe1 
1d6297e2427f1d00a5b355d6d50809cb 
Transmission-2.90.dmg

e3ad733cea9eba29e86610050c1a15592e6c77820927b9edeb77310975393574 
56b1d956112b0b7bd3e44f20cf1f2c19 
Transmission

31b6adb633cff2a0f34cefd2a218097f3a9a8176c9363cc70fe41fe02af810b9
14a4df1df622562b3bf5bc9a94e6a783 
General.rtf

d7d765b1ddd235a57a2d13bd065f293a7469594c7e13ea7700e55501206a09b5 
24a8f01cfdc4228b4fc9bb87fedf6eb7 
Transmission2.90.dmg

ddc3dbee2a8ea9d8ed93f0843400653a89350612f2914868485476a847c6484a
3151d9a085d14508fa9f10d48afc7016 
Transmission

6061a554f5997a43c91f49f8aaf40c80a3f547fc6187bee57cd5573641fcf153 
861c3da2bbce6c09eda2709c8994f34c 
General.rtf



Download
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How To Start | How To Become An Ethical Hacker

Are you tired of reading endless news stories about ethical hacking and not really knowing what that means? Let's change that!
This Post is for the people that:

  • Have No Experience With Cybersecurity (Ethical Hacking)
  • Have Limited Experience.
  • Those That Just Can't Get A Break


OK, let's dive into the post and suggest some ways that you can get ahead in Cybersecurity.
I receive many messages on how to become a hacker. "I'm a beginner in hacking, how should I start?" or "I want to be able to hack my friend's Facebook account" are some of the more frequent queries. Hacking is a skill. And you must remember that if you want to learn hacking solely for the fun of hacking into your friend's Facebook account or email, things will not work out for you. You should decide to learn hacking because of your fascination for technology and your desire to be an expert in computer systems. Its time to change the color of your hat 😀

 I've had my good share of Hats. Black, white or sometimes a blackish shade of grey. The darker it gets, the more fun you have.

If you have no experience don't worry. We ALL had to start somewhere, and we ALL needed help to get where we are today. No one is an island and no one is born with all the necessary skills. Period.OK, so you have zero experience and limited skills…my advice in this instance is that you teach yourself some absolute fundamentals.
Let's get this party started.
  •  What is hacking?
Hacking is identifying weakness and vulnerabilities of some system and gaining access with it.
Hacker gets unauthorized access by targeting system while ethical hacker have an official permission in a lawful and legitimate manner to assess the security posture of a target system(s)

 There's some types of hackers, a bit of "terminology".
White hat — ethical hacker.
Black hat — classical hacker, get unauthorized access.
Grey hat — person who gets unauthorized access but reveals the weaknesses to the company.
Script kiddie — person with no technical skills just used pre-made tools.
Hacktivist — person who hacks for some idea and leaves some messages. For example strike against copyright.
  •  Skills required to become ethical hacker.
  1. Curosity anf exploration
  2. Operating System
  3. Fundamentals of Networking
*Note this sites





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