Security Experts:

New BlackPOS Malware Uses Custom Search Method to Find Card Data

A new variant of BlackPOS (Kaptoxa), a piece of RAM scraping malware designed to target point-of-sale (PoS) systems, has been spotted in the wild by researchers at Trend Micro.

It's not surprising that new variants of BlackPOS keep emerging, considering that the source code for the malware was leaked online back in 2012. The threat is popular among cybercriminals and it is even believed to have been used in the 2013 attack against Target.

The new threat, detected by the security firm as TSPY_MEMLOG.A, is interesting for several reasons. One of them is that the malware attempts to avoid being detected by security solutions by disguising itself as antivirus software. Earlier versions hide their presence by creating services that mimic ones which are already installed.

"The malware can be run with options: -[start|stop|install|uninstall]. The –install option installs the malware with service name =<AV_Company> Framework Management Instrumentation, and the –uninstall option deletes the said service. The RAM scraping routine begins as a thread when the installed service starts. It may only start its main routine if it has successfully been registered as a service," Trend Micro threat response engineer Rhena Inocencio wrote in a blog post.

Another new feature of TSPY_MEMLOG.A is that it uses a call to the CreateToolhelp32Snapshot API to list and iterate all running processes, unlike previous variants which leveraged the EnumProcesses API.

PoS malware typically uses regex search to check the RAM for payment card data, also known as "Track data." However, this particular threat relies on a new custom search routine.

"It samples 0x20000h bytes [the 0x and h implies hex bytes] in each pass, and continues scanning till it has scanned the entire memory region of the process being inspected," Inocencio explained.

Similar to the PoS malware dubbed vSkimmer, this BlackPOS variant doesn't scan processes that don't contain any track data, including taskmgr.exe, svchost.exe, winlogon.exe, wininit.exe, cfmon.exe, services.exe, firefox.exe and chrome.exe.

Once track data is found, it is stored in a file named McTrayErrorLogging.dll and sent to a shared location within the network. This method is also used by the BlackPOS variant detected by Trend Micro as TSPY_POCARDL.AB, but TSPY_MEMLOG.A relies on a batch file (t.bat), not the "net" command, to transfer the harvested data to a specific location within the network, from where it is uploaded to a FTP server controlled by the attacker. This technique was also used in the cyberattack against Target.

Last month, the United States Secret Service revealed that the devices of more than 1,000 businesses had been infected with a piece of malware dubbed "Backoff," which is believed to have also made its way onto the computer systems at several UPS Store locations.

Kaspersky Lab recently sinkholed some Backoff C&C servers and found that most victims are in the United States and Canada. The list includes a payroll association, a liquor store chain, a global freight shipping and transport logistics company, an ISP, and a firm that manages office buildings in California.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.