Cybercriminals Hide Malware Commands in Malicious Memes

January 03, 2019

Trend Micro security researchers have discovered a new piece of malware that receives commands via malicious memes its operators published on Twitter.

The method used to conceal malicious commands is called steganographyand has long been abused by cybercriminals to hide malicious payloads inside files in order to evade security solutions. Several years ago, security researchers observed the technique being abused in exploit kitand malvertising campaigns.

The use of social media platforms such as Twitter to send commands to malware isn't new either. Malware that abuses such services has been aroundfor several years.

As part of the newly analyzedattack, the actor published two memes (images that are humorous in nature) containing malicious commands on their Twitter account. The memes were published in late October, but the account had been created last year.

The embedded command is parsed by the malware after the malicious meme is downloaded onto the victim's machine. Detected as TROJAN.MSIL.BERBOMTHUM.AA, the malware itself wasn't downloaded from Twitter, but managed to infect the victim's machine via an unknown mechanism.

The memes contained the "/print" command, which instructs the malware to take screenshots of the infected machine's desktop. The malware then sends the screenshots to a command and control (C&C) server address that it had obtained through a hard-coded URL on pastebin.com.

Once executed on an infected machine, the malware can download memes to extract and then execute the commands embedded inside. The URL address used in the attack is an internal or private IP address, which the security researchers believe is a temporary placeholder used by the attackers.

Based on the commands received via Twitter, the malware could capture the screen, retrieve a list of running processes, capture clipboard content, retrieve the username from infected machine, or retrieve filenames from a predefined path (such as desktop, %AppData% etc.), the security researchers reveal.

Twitter has already suspended the account used in these attacks.

"Users and businesses can consider adopting security solutions that can protect systems from various threats, such as malware that communicate with benign-looking images, through a cross-generational blend of threat defense techniques," Trend Micro concludes.