Vulnerabilities

The Boston Marathon bombings, RedKit and a malware zoo

Just some hours after the bombings during the Boston Marathon we already had several spam campaigns using that subject to infect users. It seems that cybercriminals don't respect anything, did we really expect something different? :p

On the past Wednesday I received four emails talking about the Boston incident. They were really suspicious, just a URL in the body, the URLs had just an IP instead of a good domain...I think someone was in a rush trying to profit from this as soon as possible, while it was still on the news...
 

 
The subjects were:
 

BREAKING - Boston Marathon Explosion 
Explosion at the Boston Marathon
Aftermath to explosion at Boston Marathon
Explosions at the Boston Marathon

 
And the URLs I saw:
 

hxxp://94.28.49 .130/boston.html 
hxxp://78.90.133 .133/boston.html
hxxp://118.141.37 .122/news.html
hxxp://110.92.80 .47/news.html

 
These URLs leaded to a simple webpage with six iframes. Five of them pointed to real videos about the tragedy and the other one redirected to a RedKit exploit kit which was trying to exploit a CVE-2012-1723 Java vulnerability (take a look at the vulnerability explanation). Also, a Meta Refresh Tag was leading to this URL:
 

Troopers13 conference - Day 2

I started the second day with the Marcus Niemietz's talk “UI Redressing Attacks on Android Devices” about the chances to cheat on the users using hidden layers to perform unwanted actions. After this, another mobile subject, Peter Kieserberg shared his ideas about the use of QR codes as a vector attack.

After lunch it was Sergey Bratus and Travis Goodspeed's turn to speak about the security of USB ports, telling how it is possible to compromise the whole system via a unattended USB port. This was a really interesting talk that one can explore by himself taking a look at some good documentation on Travis' blog.

 

 

The talk “We Came In Peace – They Don’t: Hackers vs. CyberWar” by FX was next. He gave his opinion about the actual cyberwarfare and the difference between the point of view of Governments and cybersecurity experts about this subject. Some ideas from his talk: avoid the use of 0-days as weapons through Full-Disclosure, learn how to protect you playing CTFs and don't give up.
 

Troopers13 conference - Day 1

Until now I had not had enough time to write about my experience at my first Troopers. Due to some good comments about it I had had in mind going to Troopers since some time ago, but for one reason or another I hadn't been able to do it. Last year I had the opportunity to share table with Enno Rey, Troopers organizer and CEO of ERNW, at BlackHat Europe. That time I saw they were a good team and good people, and this year, living closer to Heidelberg, I had no excuses to go.

I arrived in Heidelberg at 3:30AM after 9 hours on the road due to the bad weather conditions. I was able to rest to be ready for the talks in the next morning. I missed the keynote by Rodrigo Branco, but I heard that it was really good. The first talk I attended was “Paparazzi over IP” by Daniel Mende and Pascal Turbing about hacking a CANON camera, equipped with a wireless adapter and other features. The result was that it was possible to see all the photographs taken, control the device remotely and intercept the images while they were about to be sent to a cloud storage.

 

 

New peepdf v0.2 (Black Hat Vegas version)

Last week I was in Vegas presenting the new release of peepdf, version 0.2. Since my release at Black Hat Amsterdam some months ago I hadn't created a new package so it was time to do it. You can now download the new package here or use “peepdf -u” to update it to the latest version.

 

 
So the main new features, besides the fixed bugs, are the following:

  • Added support for AES in the decryption process: Until now peepdf supported RC4 as a decryption algorithm but AES was a must. Now here it is, so no more worries for decrypted documents. I will be ready for new changes in the decryption process, someone in Vegas told me that the next AES modification for PDF files is coming...

 

 

peepdf supports CCITTFaxDecode encoded streams

Stream filters, as I said some time ago, are a good way of obfuscating PDF files and hide Javascript code, for instance. Some weeks ago a post related to the use of the /CCITTFaxDecode filter was published by Sophos, although the Malware Tracker guys tracked a similar document created more than one year ago. Bad guys were using the /CCITTFaxDecode filter with some parameters to obfuscate the documents and try to bypass analysis tools and Antivirus. This filter was not supported by peepdf until the moment, so Binjo ported the Origami decoder to Python to include it (Thanks man!). Today I have uploaded the code and now peepdf also supports this filter :)

I've performed a quick analysis of the Sophos' document (6cc2a162e08836f7d50d461a9fc136fe) and it seems to work well:

 

 

We can identify two known vulnerabilities and it seems that object 30 contains Javascript code. If we take a look at the filters used in this stream we see that peepdf has been able to decode the /CCITTFaxDecode filter without problems:

 

New version of peepdf (v0.1 r92 - Black Hat Europe Arsenal 2012)

Last week I presented the last version of peepdf in the Black Hat Europe Arsenal. It was a really good experience that I hope I can continue doing in the future ;) Since the very first version, almost one year ago, I had not released any new version but I have been frequently updating the project SVN. Now you can download the new version with some interesting additions (and bugfixes), and take a look at the overview of the tool in the slides. I think it's important to mention that the version included in the Black Hat CD and the one in the Black Hat Arsenal webpage IS NOT the last version, this IS the last version. I've asked the Black Hat stuff to change the version on the site so I hope this can be fixed soon.
 

Sex, Exploit Kits and Ransomware

Each of us has his own preferences: some people love Lady Gaga or Justin Bieber, others Rocco Siffredi or Laura Lion. The love for the latter can be dangerous if you are not aware of security problems when you have a non-updated system, and it's possible you end with an infected system asking for money to recover the control of the machine.

 

 

This was an interesting situation so I tried to help my friend. In this case, just after the desktop appeared, a full-screen window showed. It was a warning from the Spanish police ("Cuerpo Nacional de Policía") saying that the system had been blocked because it had been used to perpetrate illegal actions like child pornography, terrorism and violence against children: "Fue detectado un caso de actividad ilegal. El sistema operativo fue bloqueado por violación de las leyes de España!". A warning like this can be shocking for a normal user, so social engineering was working here. However, this warning was also asking for 100€ to be paid via Ukash or Paysafecard as a fine for this behaviour and in order to restore the system. This part can be a bit strange and maybe makes the victims call the police very quickly. Once this window appeared no other action was possible, like execute the Task Manager or return to the desktop, just enter a code to pay.

 

 

Dynamic analysis of a CVE-2011-2462 PDF exploit

After the exploit static analysis some things like the function of the shellcode were unclear, so a dynamic analysis could throw some light on it. When we open the exploit without the Javascript code used for heap spraying we obtain an access violation error in rt3d.dll. If we put a breakpoint in the same point when we launch the original exploit we can see this (better explanation of the vulnerability):

 

Instead of showing an access violation the CALL function is pointing to a valid address in icucnv36.dll, 0x4A8453C3. This address is not random and it's used in the Javascript code to perform part of the heap spraying:

 

 

 

Static analysis of a CVE-2011-2462 PDF exploit

CVE-2011-2462 was published more than one month ago. It's a memory corruption vulnerability related to U3D objects in Adobe Reader and it affected all the latest versions from Adobe (<=9.4.6 and <= 10.1.1). It was discovered while it was being actively exploited in the wild, as some analysis say. Adobe released a patch for it 10 days after its publication. I'm going to analyse a PDF file exploiting this vulnerability with peepdf to show some of the new commands and functions in action.

As usual, a first look at the information of the file:

info

I've highlighted the interesting information of the info command: one error while parsing the document, one object (15) containing Javascript code, one object (4) containing two ways of executing elements (/AcroForm, /OpenAction) and one U3D object (10), suspicious for its known vulnerabilities, apart of the latest one.

So we have several objects to explore, let's start from the /AcroForm element (object 4):

BlackHole leading to Feodo: Bank of America account frozen

I've received a Christmas gift some hours ago. In fact there were two gifts but only one has survived the trip. They are from Russia...with love. Of course I'm talking about two e-mails I've received with two suspicious links. Even the e-mail bodies were suspicious, I think they have packed very quickly my gifts or they are not very attentive to me...:( The From field included "bankofamerica" and the Subject "Accountfrozen" so I suppose this means that my Bank of America account is frozen, right?

After some redirections we can find the typical obfuscated Javascript code made in BlackHole:
 

After decoding the Javascript code we obtain the next step, also related to BlackHole. This time I can only see a unique Flash exploit trying to download and execute a binary from the same domain where the exploit kit is located (shellcode is XORed with 0x28).

ZeuS P2P distribution campaign: ACH transaction canceled

Our team (S21sec) has detected a ZeuS trojan distribution by email campaign that has been running for some days. The malicious emails include a link to a supposed report about a cancelled transaction, which is actually an HTML page that loads Javascript code into the victim’s browser. This code tries to exploit different vulnerabilities in Java, Flash and PDF to install ZeuS 2.0 on the system. This is one of the latest versions of ZeuS which uses P2P as part of its infrastructure (Murofet 2.0).
 
The subject of the emails detected so far is “ACH transaction canceled” and in the body of the mail there is information about a supposed transaction that has been cancelled. If the victim wants further information then they have to visit a link that contains a report about the transaction:

For a few seconds the victim sees a screen indicating that they must wait. Meanwhile 4 scripts, stored on different domains are loaded into user’s browser. They are little more than simple redirections towards the site where the code (that will attempt to perform the exploitation) resides.

Analysis of a malicious PDF from a SEO Sploit Pack

According to a Kaspersky Lab article, SEO Sploit Pack is one of the Exploit Kits which appeared in the first months of the year, being PDF and Java vulnerabilities the most used in these type of kits. That's the reason why I've chosen to analyse a malicious PDF file downloaded from a SEO Sploit Pack. The PDF file kissasszod.pdf was downloaded from hxxp://marinada3.com/88/eatavayinquisitive.php and it had a low detection rate. So taking a look at the file with peepdf we can see this information:

In a quick look we can see that there are Javascript code in object 8 and that the element /AcroForm is probably used to execute something when the document is opened. The next step is to explore these objects and find out what will be executed:

ToorCon Seattle 2011

As I mentioned in the previous post, just after Source Seattle some days ago, the ToorCon (also in Seattle) began. Some speakers took advantage of this to present the same or different presentations at both conferences. Friday the 13th was the opening day, with a small party, but the presentations didn’t begin until the following day. There were thirty talks in total, each delivered in a 15 minute period of time, with a short break for lunch. It was an entire day of presentations, from 8:30 till 10:30, quite a day!
 

Source Seattle 2011

Some days ago, Source Seattle (USA) took place. It is the first time it has taken place in Seattle and although the attendance couldn’t match the Boston conference, the atmosphere was magnificent. It began on Tuesday the 14th with an event for the speakers and organizers to get to know each other and enjoy a beer with some tasty Asian cuisine. I was the representative of the S21sec e-crime team with a speech about banking Trojans.

The talks began on Wednesday the 15th and the agenda was divided into two tracks, one dedicated to technical themes and the other centred on the business world. The first day, the following themes (amongst others) were touched on: evaluation of necessary expenses in security, the application of the law in cybercrime matters, threat modelling, forensic memory analysis of Android’s Dalvik Virtual Machine and my speech about the evolution of fraud through banking Trojans.

Obfuscation and (non-)detection of malicious PDF files

More than two months ago I talked at Rooted CON (Madrid) about some techniques to obfuscate and hide malicious PDF files. I gave the same speech at CARO 2011 (Prague) some days ago with updated slides and a demo of peepdf.

The idea is that it's possible to use some malformations in the documents, like those commented by Julia Wolf, and the PDF specification itself in order to keep the files hidden from Antivirus engines and parsers. Bad guys can effectively use it to create an undetectable exploit and use it as an attacking vector. Some of the techniques are the following:

 

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