Banking Trojan hijacks live chat to run real-time fraud

A new strain of financial malware is hijacking live chat sessions in a bid to hoodwink business banking customers into handing over their banking login credentials or into authorising fraudulent transactions.

The attack is being carried out using the Shylock malware platform*, using a configuration that runs a browser-based man-in-the-middle attack. The assault – which targets business banking customers rather than consumers – kicks in when a victim logs into their online banking application.

Sessions are suspended, supposedly to run security checks (on the pretext that the "system couldn't identify your PC"), before a web-chat screen under the control of hackers is presented to victims. But instead of talking to a customer service rep, the mark is actually chatting to cybercrooks, who will attempt to hoodwink victims into handing over login credentials or other information needed to authorise fraudulent transactions. Unbeknownst to the victims, the fraudsters are relaying authorisation data to the victim's bank during their conversation, carrying out a concurrent fraud in real time.

"This web injection is followed by an elaborate web-chat screen, which is implemented in pure HTML and JavaScript," Trusteer explains. "Within two to three minutes, if the user's login is valid ... the fraudster engages in a live online chat session with the victim. This exchange is apparently used to gather more information from the victim. The session may even be used to perform real-time fraud by enticing the victim to sign/verify fraudulent transactions that Shylock is initiating in the background."

Phishing attacks that incorporate live chat have appeared before but these assaults (like this one detected by RSA in 2009) involved tricking victims into visiting phishing sites. Cybercrooks have refined this approach with the latest attack by embedding similar functionality into a malware platform so that they can present the attack as soon as victims log into banking applications from compromised PCs, avoiding the need to trick victims into visiting a phishing site they have established.

Phishing sites are subject to rapid takedown and blacklisting, so avoiding this step in the process is a major advantage to crooks.

Trusteer has more detail on the attack in a blog post here. ®

Bootnote

*Shylock is so named because every new build bundles random excerpts from Shakespeare's The Merchant of Venice in its binary. The malware, which first appeared last September, has claimed a significant increase in infected machines over recent weeks, Trusteer separately warned earlier this month. Shylock uses a battery of tricks to escape detection by anti-virus scanners, as explained here.