Windows Mailslots Steal POS Data Abused by FastPOS Malware

Recently, the developers of FastPOS malware have updated their trojan with a new data exfiltration mechanism which abuses the Windows Mailslots mechanism to store data before exfiltration from infected systems.

The latest version of POS (Point Of Sale) malware appeared in June, when security experts from Trend Micro noticed some ads for it on the underground carding forums. The analysis showed that the newly-found malware family is focused on speed and sacrificed stealth, which is an opposite approach to how most POS malware operate today. After the initial detection, Trend Micro continued the analysis of the new malware and found traces of FastPOS activity dating back to March, last year.

Apart from the above-mentioned, the researchers discovered that the FastPOS operator updates his malware every September, just in time for the holiday season. As September has passed now, Trend Micro has published new details on the latest FastPOS version. According to the security company, the new malware has the ability to infect Windows computers running both 32-bit and 64-bit architectures. Also, FastPOS uses two main modules (memory scrapper and keylogger), and has changed the way it works at the OS process level.

The old version of FastPOS operated from one self-contained process, while in the recent version, its main and secondary modules operate from across different OS processes, making them harder to remove, but also louder for AV software.

Actually, Trend Micro claims that detecting the HTTP streams through which the malware steals credit card data from POS software is quite easy since the data is not encrypted.
However, the change which stood out the most in this recent version was how FastPOS stored collected data before sending it to its C&C server.

Identically to the past iterations, the malware saved all data inside the computer’s memory (RAM) to avoid creating local files. In fact, this is a planned feature due to the fact that the malware never intends to keep the stolen information for extended amounts of time, hence the malware’s name – “Fast POS.”

The latest malware version abuses a Windows mechanism named Mailslots, which are pseudo-files (temporary files) residing only in the computer’s RAM, used to store inter-process communications (IPC). Due to the fact that the FastPOS modules inject themselves in processes such as explorer.exe and services.exe, they have easy access to create mailslots and store stolen data.

Another POS malware called LogPOS also abuses mailslots to steal data it collects from POS software. Windows mailslots fit perfectly with FastPOS’ default mode of operation, which exfiltrates data as soon as the user presses Enter on a keyboard or swipes a card through a POS terminal.

“Given FastPOS’s emphasis on speed, it is mainly designed to target businesses whose primary network gateways have a relatively lesser footprint,” the Trend Micro team says.

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