On 20 March, Russian law enforcement agencies announced the arrest of a cybercriminal gang involved in stealing money using the Carberp Trojan. This is very good news, but unfortunately does not mark the end of the Carberp story.

Evidently, those arrested were just one of the criminal gangs using the Trojan. At the same time, those who actually developed Carberp are still at large, openly selling the Trojan on cybercriminal forums.

Here is a recent offer for the ‘multifunctional bankbot’, which appeared on 21 March:

Post was updated 19.03.2012 (see below)

In the last few days a malicious program has been discovered with a valid signature. The malware is a 32- or 64-bit dropper that is detected by Kaspersky Lab as Trojan-Dropper.Win32.Mediyes or Trojan-Dropper.Win64.Mediyes respectively.

Numerous dropper files have been identified that were signed on various dates between December 2011 and 7 March 2012. In all those cases a certificate was used that was issued for the Swiss company Conpavi AG. The company is known to work with Swiss government agencies such as municipalities and cantons.

Information about the Trojan-Dropper.Win32.Mediyes digital signature

On 3 December, we noted a rapid growth in the number of detections for exploits targeting the vulnerability CVE-2011-3544 in Java virtual machine. The vulnerability was published on 18 October, but malicious users have only recently begun to make active use of it. It can be used by exploits in drive-by attacks to download and launch malicious programs.

Number of unique detections of Exploit.Java.CVE-2011-3544

According to KSN data, most of the exploits targeting CVE-2011-3544 are used in the BlackHole Exploit Kit, which is currently the most popular exploit pack.

We analyzed the latest BlackHole kits. The sites that carry out drive-by attacks with the help of BlackHole turned up quite an old exploit – a PDF file that targets the vulnerability CVE-2010-0188, and a new Java exploit targeting the vulnerability CVE-2011-3544. The corresponding files are circled in red in the screenshot below.

A screenshot of the list of files intercepted when visiting websites where BlackHole is installed

Brian Krebs reports that the creators of BlackHole have successfully integrated the new exploit into their kit. According to KSN statistics, the new exploits attack users in Russia, the US, the UK and Germany. This appears to be related to the fact that new exploits that are integrated in BlackHole and target the vulnerability CVE-2011-3544, install the Trojan Carberp that steals banking data, as well as SMS blockers. SMS blockers are mostly used in Russia, while Trojan bankers attack users in developed countries.

Once again we see that malware writers are forging ahead and are continually improving their creations. It is, therefore, critical that all users install Java updates from Oracle in a timely manner. The patch for (among other things) the CVE-2011-3544 vulnerability can be downloaded here.

Not so long ago we wrote about cybercriminals using infected computers to generate virtual money via Bitcoin. A couple of days ago we discovered a malicious program called Trojan-Downloader.Win32.MQL5Miner.a which also uses the resources of infected computers, but this time to make money in MQL5 Cloud Network, a distributed computing network.

The MQL5 Cloud Network site

MetaQuotes is a developer of software for financial markets. Several weeks ago, information appeared on the net that the company was offering to pay users to participate in distributed computing. Apparently, this is what attracted malicious users to the new cloud service.

Google search results for the phrase: “MQL5 Cloud Network money”

There are grounds to believe that the malicious program spreads via email. Having infected a computer, the malicious program first determines if the operating system is 32-bit or 64-bit. It then downloads the appropriate version of the official software from MetaQuotes SoftWare. MQL5Miner then launches the service to participate in the cloud computing network. But the cybercriminals specify their own account data and receive the payments for any distributed computing operations that are performed on an infected machine.

A window from the legitimate MetaQuotes software

When it comes to making money, cybercriminals don’t miss a trick. That includes exploiting the resources of infected computers without their owners’ knowledge or consent.

We have notified MetaQuotes about the account being used by cybercriminals.

Since June 2011 we have seen a substantial decrease in the number of fake antivirus programs. Right now we are observing 10 000 daily attempts to infect users with Trojan-FakeAV; back in June the figures were 50-60,000.

The daily number of attempted infections using Trojan-FakeAV in the past 5 months

Modification of the hard drive areas responsible for the initial loading of the system has become increasing popular with cybercriminals. Moreover, cybercriminals have now moved on from just modifying the MBR (master boot record) to infecting the code of the NTFS loader.

We recently discovered an interesting piece of malware — Cidox. It is peculiar in that it infects the load area code of the boot partition on the hard drive.

The master file Trojan-Dropper.Win32.Cidox “carries on board” two driver rootkits (Rootkit.Win32/Win64.Cidox). One is compiled for 32-bit platforms, the other for 64-bit platforms.

The source component of Cidox makes the following modifications to the beginning of the hard drive:

• Saves the relevant driver to free sectors at the beginning of the hard drive;
• It chooses the section marked as the boot partition in the MBR partition table for infection. It is important to note that it only infects partitions with the NTFS file system.
• Writes part of its code over Extended NTFS IPL (Initial Program Loader), which is responsible for parsing the MFT table (Master File Table), searching for the file with the loader in the root directory of the section (ntldr — pre-Vista, bootmgr — Vista+), reading this file form the disk and transferring control to it. At the same time the original contents of Extended NTFS IPL are encrypted, saved and added to the end of the malicious code.

The Virus Lab recently came across a very interesting sample – a downloader containing two drivers and which downloads fake antivirus programs developed for both PC and Mac platforms. The malicious program is downloaded and installed using the BlackHole Exploit Kit. The latter contains exploits targeting vulnerabilities in JRE (CVE-2010-0886, CVE-2010-4452, CVE-2010-3552) and PDF.

Both drivers are standard rootkits with rich functionality. One of them is a 32-bit and the other a 64-bit driver. The 64-bit driver is signed with a so-called testing digital signature. If Windows – Vista and higher – was booted in ‘TESTSIGNING’ mode, the applications can launch the drivers signed with a testing signature. This is a special trap-door which Microsoft has left for driver developers so they can test their creations. Cybercriminals have also made use of this loophole: they execute the command ‘bcdedit.exe –set TESTSIGNING ON’ which allows them to launch their driver without a legitimate signature.

The following description refers to both rootkits because, apart from the platforms, their functionality is identical. Once the driver is successfully loaded and running on the system, it’s difficult to get rid of it. The rootkit blocks the launch of drivers belonging to anti-rootkit and antivirus products. This is done by using lists of file names for specific drivers and strings for which the rootkit searches the Security section of the DataDirectory array of the image being loaded. If the rootkit detects an “untrusted” driver being loaded, the bytes at the entry point of the image are changed, preventing it from loading correctly.

Fragment of the rootkit containing search strings used to block antivirus drivers

The rootkit protects the “main” application by hooking ZwOpenProcess / ZwOpenThread in SDT (only on 32-bit versions of Windows) and using object manager callbacks to access “trusted” applications. The file system is also monitored by connecting to file system stacks and the registry – by using registry callbacks.

This rootkit is yet more proof (after TDSS) that it’s unnecessary to bypass Patch Guard-а in order to implement rootkit functionality on 64-bit platforms.

The downloader is written in C++ and is itself not protected. Its main task is to install and launch the relevant driver (32- or 64-bit), then download and launch a list of files from URLs. Interestingly, one link leads to Hoax.OSX.Defma.f which we recently wrote about. Most importantly, the rootkit tries to run it…under Windows! It appears that the developers of the latest rogue AV program for MacOS are actively distributing it via intermediaries, who don’t really understand what it is they are supposed to install on users’ computers.

Fragment of the malicious code that downloads and launches the file

Kaspersky Lab products successfully detect and neutralize both Trojan-Downloader.Win32.Necurs.a and Rootkit.Win32.Necurs.a / Rootkit.Win64.Necurs.a.

We recently discovered a new bootkit, i.e. a malicious program which infects the hard drive’s boot sector. Kaspersky Lab detects it as Rookit.Win32.Fisp.a. The bootkit is distributed by Trojan-Downloader.NSIS.Agent.jd. The Trojan infects the computers of users who try to download a video clip from a fake Chinese porn site.

This downloader is remarkable in that it downloads other malicious programs using a NSIS engine and stores all links in the relevant NSIS-script.

Fragment of the NSIS script for Trojan-Downloader.NSIS.Agent.jd

The dropper Rootkit.Win32.Fisp.a is among the files downloaded by the Trojan-downloader. This malicious program infects the hard drive’s boot sector. More specifically, it saves the old MBR to the third sector and replaces it with its own. Starting with the fourth sector, it installs an encrypted driver and the remaining code.

Fragment from the start of the hard disk infected by Rootkit.Win32.Fisp.a

Programs for cracking commercial software are, sadly, not unpopular. They have also caught the attention of malware writers, who prepared a couple of surprises for those who don’t mind a free ride every now and then.

A short time ago, we detected a Trojan dropper which passes itself off as a key generator for Kaspersky Lab products. The file’s name is kaspersky.exe.

Once launched, the file displays a key generator window prompting the user to select a product. After one of the options is selected, the program proceeds to generate a key.

Keygen window

While the freebie lover is waiting for the result, two pieces of malware that were stealthily installed and launched by the dropper make themselves at home on the PC.

One of these is detected by Kaspersky Lab as Trojan.MSIL.Agent.aor. It steals registration data for other programs, as well as passwords, mostly for online games. It rather considerately stores all the stolen data in one file. A fragment of the file is shown on the screenshot below.

In the last few days we have discovered that spam messages with malicious links are being sent via instant messenger services. It turns out that the mailings were carried out by the Zeroll IM worm. A bot generated various messages depending on the language of the recipient. Here are a few of them:

“Wie findest du das Foto?”
“seen this?? :D %s”
“This is the funniest photo ever!”
“bekijk deze foto :D”
“uita-te la aceasta fotografie :D”

Like lots of other similar incidents, the cybercriminals have made use of social engineering, asking users to look at pictures with alluring names. At the end of the message there is a link such as http://www.facebook.com/l.php?u=********.org/Jenny.jpg. As well as the link to the Jenny.jpg file the messages included similar links to Sexy.jpg.

The page that the http://www.facebook.com/l.php?u= link leads to is not actually malicious – it contains a warning from Facebook telling the user they are leaving the site.

Facebook warning

If you add a link to any random site after ‘l.php?u=’, then a window opens with a warning from Facebook. However, after the user clicks the ‘Continue’ button the link will direct the user to the corresponding site. This mechanism was used by the cybercriminals to make the link to the malicious site look more legitimate.

When the browser redirects to the page ********.org/Jenny.jpg it leads to the file PIC1274214241-JPG-www.facebook.com.exe which is then launched by unsuspecting users. Hereafter, the terms jenny.jpg and sexy.jpg refer to this executable file.

After analyzing jenny.jpg and sexy.jpg it turned out that they were typical downloaders, protected by packers and written in Visual Basic.

Fragment of the downloader code after the jenny.jpg file is unpacked in full

The downloaders’ job is typical for these types of program – download another malicious program to the infected computer. In this case, it’s the file srce.exe. So that the user doesn’t suspect anything, the downloaders also open the picture that was promised in the original spam message. The picture is downloaded from the Internet (the link can be seen in the screenshot).

So what is srce.exe? It’s a dropper + downloader whose outer shell is also written in Visual Basic. It downloads IM-Worm.Win32.XorBot.a which uses Yahoo Messenger to send out messages to users.

So what we have here is a link to a page on Facebook being used in instant messaging spam instead of a direct link to a malicious object. You could say that Facebook is being used a service along the lines of bit.ly: it allows links to be modified so that they are directed via the Facebook domain.

Zeroll is still actively sending out spam. The messages contain links to different files, but with similar names such as Girls.jpg and Marisella.jpg. And even though people already know they shouldn’t just click any old links, even if it was sent by someone on their contact list, it’s worth reminding everyone again. If nothing else, cybercriminals are creative, and the Zeroll spam once again confirms this.