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Updated: 2 hours 53 min ago

Windows Previous Versions against ransomware, (Thu, Jul 24th)

12 hours 15 min ago

One of the cool features that Microsoft actually added in Windows Vista is the ability to recover previous versions of files and folders. This is part of the VSS (Volume Shadow Copy Service) which allows automatic creation of backup copies on the system. Most users “virtually meet” this service when they are installing new software, when a restore point is created that allows a user to easily revert the operating system back to the original state, if something goes wrong.

However, the “Previous Versions” feature can be very handy when other mistakes or incidents happen as well. For example, if a user deleted a file in a folder, and the “Previous Version” feature is active, it is very easy to restore a deleted file by clicking the appropriate button in the Properties menu of the drive/folder that contained the deleted file. The user can then simply browse through previous versions and restore the deleted file, as shown in the figure below:


You can see in the figure above that there are actually multiple versions of the Desktop folder that were saved by the “Previous Versions” feature. A user can now simply click on any version he/she desires and browse through previous files.

How can this help against Cryptolocker and similar ransomware? Well simply – when such ransomware infects a machine, it typically encrypts all document files such as Word and PDF files or pictures (JPG, PNG …). If the “Previous Versions” feature is running, depending on several factors such as allocated disk space for it as well as the time of last snapshot (since “Previous Versions” saves files comparing to the last snapshot, which would normally take place every day), you just might be lucky enough that *some* of the encrypted files are available in “Previous Versions”.

Monitoring “Previous Versions” activities

As we can see, by using this feature it is very simple to restore previous files. This is one of the reasons why I see many companies using this feature on shared disks – it can be very handy in case a user accidentally deleted a file.

However, there are also security implications here. For example, a user can restore a file that was previously deleted and that you thought is gone. Of course, the user still needs access rights on that file – if the ACL does not allow him to access the file he won’t be able to restore it, but in case an administrator set ACL’s on a directory, which is typically the case, and everything else below it is inherited, the user might potentially be able to access a file that was thought to be deleted.

This cannot be prevented (except by changing ACL’s, of course), so all we can do in this case is to try to monitor file restoration activities. Unfortunately, Windows is pretty (very?) limited in this. The best you can do is to enable Object Access Audit to see file accesses and then see what a particular user accessed. That being said, I have not been able to stably reproduce logs that could tell me exactly what version the user accessed – in some cases Windows created a log such as the following:

Share Information: Share Name: \\*\TEST Share Path: \??\C:\TEST Relative Target Name: @GMT-2014.07.02-11.56.38\eula.1028.txt

This is event 5145 (“A network share object was checked to see whether client can be granted desired access”), and it is visible which copy was accessed but, as I said, I was not able to have this event generated by this constantly.

Conclusion

The “Previous Versions” feature is very handy in cases when you need to restore a file that was accidentally deleted or modified and can sometimes even help when a bigger incident such as a ransomware infection happened. Make sure that you use this feature if you need it, but also be aware of security implications – such as the fact that it automatically preserves deleted files and their modified copies.

Finally, for some reason Microsoft decided to remove, actually modify this feature in Windows 8. The “Previous Versions” tab does not any more exist in Explorer (actually it does, but you need to access files over a network share). For saving local files Windows 8 now use a feature called “File History”. It needs to be manually setup and it needs to have an external HDD which will be used to save copies of files. This is definitely better since, if your main HDD dies, you can restore files off the external one, but keep in mind that it needs to be setup manually. Finally, if you use EFS to encrypt files, the “File History” feature will not work on them.

--
Bojan
​bojanz on Twitter
INFIGO IS

(c) SANS Internet Storm Center. https://isc.sans.edu Creative Commons Attribution-Noncommercial 3.0 United States License.
Categories: Vulnerability Pipes

Bugtraq: KL-001-2014-003 : Microsoft XP SP3 MQAC.sys Arbitrary Write Privilege Escalation

Tue, 07/22/2014 - 08:08
KL-001-2014-003 : Microsoft XP SP3 MQAC.sys Arbitrary Write Privilege Escalation
Categories: Vulnerability Pipes

Bugtraq: KL-001-2014-002 : Microsoft XP SP3 BthPan.sys Arbitrary Write Privilege Escalation

Tue, 07/22/2014 - 08:08
KL-001-2014-002 : Microsoft XP SP3 BthPan.sys Arbitrary Write Privilege Escalation
Categories: Vulnerability Pipes

Bugtraq: Microsoft MSN HBE - Blind SQL Injection Vulnerability

Mon, 07/21/2014 - 08:07
Microsoft MSN HBE - Blind SQL Injection Vulnerability
Categories: Vulnerability Pipes

Keeping the RATs out: the trap is sprung - Part 3, (Sat, Jul 19th)

Sat, 07/19/2014 - 01:28

As we bring out three part series on RAT tools suffered upon our friends at Hazrat Supply we must visit the centerpiece of it all. The big dog in this fight is indeed the bybtt.cc3 file (Jake suspected this), Backdoor:Win32/Zegost.B. The file is unquestionably a PEDLL but renamed a .cc3 to hide on system like a CueCards Professional database file.
Based on the TrendMicro writeup on this family, the backdoor drops four files, including %Program Files%\%SESSIONNAME%\{random characters}.cc3
This indicates that bybtt.cc3 is one of the dropped files rather than the source file.
Per the Microsoft writeup for Backdoor:Win32/Zegost.B, once installed, it attaches its code to the legitimate Windows process, svchost.exe.
This is therefore likely the svchost.exe (MD5 20a6310b50d31b3da823ed00276e8a50) that Jake sent us. It's all coming together.
The Microsoft writeup also states that after connecting to the C2 server it receives commands to copy, execute, download, and delete files, gather information from the RAS phonebook, and capture screenshots. I'll confirm each of these steps from strings or a specific tool.
Unfortunately, bybtt.cc3 wouldn't run easily in my sandbox (it's a PEDLL and yes, I know it can be done but there's only so much time in the day) but I learned or confirmed everything I needed to create IOCs for you.
First, this sample connects to ip.sousf8.com and while its registered to Peng Peng (um, yeah) the server is actually in the US.
What I really didn't like is that searches for sousf8.com prove that its been embedded as Louis Vitton forum SPAM and other evil crap that point to hxxp://fz.sousf8.com. Do not freaking go there please.
This domain points to 142.4.120.9. Jake reported to us, based on network connections and NetFlow analysis that he had RDP (TCP 3389) connections to 142.4.120.8 using mylcx.exe which we've already discussed. What what!? Oh, boy. So again, these server are in San Jose, CA but they're registered to vpsbus in...wait for it...please hold...prepareth thy shocked face...Jinjiang, in the province of Fujian, in the country of...China.
The three domains hosted on 142.4.120.9 are 9uufu.com, sousf8.com, taobaofu.com.
The ASN for these IPs belong to PEG TECH INC, a notorious spammer
According to Wepawet, who says that fz.sousf8.com is benign, that flow includes a redirect from hxxp://cnzz.mmstat.com to hxxp://pcookie.cnzz.com. Again, please don't. Both are immediately associated with Troj/Clicker-GL (more crap adware).
There are all kinds of malicious attributes in the bybtt.cc3 file too, in addition to all the IOC fodder above.
According to HookAnalyser, there's a ton of what looks like NOP padding in this sample.
[!] Found 373 traces of NOP instructions (a potential shellcode - Suspicious)  
[-] At the offset 00001109, found: '\x90\x90\x90\x90\x90\x90\x90'
And it notes the fact that:
[!] Executable is Debug aware
[!] Executable could spawn a new process
[!] Executable can enemurate processes
[!] Executable could hook to other processes
[!] Executable is potentially anti-debug aware
Yep.

Strings confirms the RAS phonebook reference from above, not two lines removed from the hostile domain:
Microsoft\Network\Connections\pbk\rasphone.pbk
%USERPROFILE%\Application Data\Microsoft\Network\Connections\pbk\rasphone.pbk
Global\b%d_%dj
+@22220Sdag892+
ip.sousf8.com

References to GDI32.dll and CreateCompatibleBitmap are indicative of the screencapture attribute, and there are way too many elements to its capability to "copy, execute, download, and delete files" to spell each out but Figure 1, created using PeStudio helps confirm.

Figure 1

What a swirling vortex of nastiness. There are so many rabbit holes to go down here, but I promised you IOCs.
I'm not going to go for file name or size or hashes, because they won't match. I'm working from one of the dropped files and as we've seen there's much randomization.
But we know for sure the related domain names, IPs, and we know thanks to Jake who teased a lot of this from the running server during his IR process, that it creates specific registry keys (PeStudio confirmed as did strings). Figure 2 is the IOC build.


Figure 2

Its cool to match the great work Jake did during IR with static analysis and turn it into what is hopefully actionable intelligence for you, dear reader.
I've posted the IOC XML files for you:

  1. http://holisticinfosec.org/iocs/464bfac7-9b16-4acb-9951-2095b6ca3b3e.ioc
  2. http://holisticinfosec.org/iocs/7d540cb4-5a52-46e4-9465-081e6735cb3d.ioc
  3. http://holisticinfosec.org/iocs/dea382df-9592-4528-b9e5-fef136e30805.ioc

Remember that IOCs change quickly and that another very related sample may exhibit entirely different indicators. So don't treat these as a panacea, but do use them as reference for your hunt and detect missions. Please feel free to enhance, optimize, tune, improve, criticize, and assassinate the character of the IOCs; they're always a work in progress, I won't be hurt.

Good luck and let us know how it goes!

Cheers.

Russ McRee | @holisticinfosec

(c) SANS Internet Storm Center. https://isc.sans.edu Creative Commons Attribution-Noncommercial 3.0 United States License.
Categories: Vulnerability Pipes

Vuln: Microsoft Internet Explorer CVE-2014-1799 Remote Memory Corruption Vulnerability

Thu, 07/17/2014 - 19:00
Microsoft Internet Explorer CVE-2014-1799 Remote Memory Corruption Vulnerability
Categories: Vulnerability Pipes