OddJob Banking Trojan Hijacks Sessions, Bypasses Logout Attempts

Researchers at Trusteer have uncovered a new banking Trojan that takes control of the online banking sessions of its victims and keeps them open despite user attempts to logout.

The Windows Trojan, dubbed OddJob, was actually discovered a few months ago being used by cyber-thieves in Eastern Europe to attack customers around the world, including the United States and Poland. The firm previously kept its findings quiet due to ongoing law enforcement investigations that have now been completed, Amit Klein, Trusteer’s CTO, explained.

The Trojan is designed to intercept user communications through the browser, thereby stealing/injecting information and terminating user sessions inside Internet Explorer and Firefox. Among its key features is its ability to bypass the logout request of a user to terminate their online session. According to Klein, because the interception and termination is carried out in the background, the legitimate user thinks they have logged out, when in fact the fraudsters remain connected - allowing them to maximize their profit from the compromise.

"This is a completely new piece of malware that pushes the hacking envelope through the evolution of existing attack methodologies," Klein blogged. "It shows how hacker ingenuity can side-step many commercial IT security applications traditionally used to defend users' digital - and online monetary - assets."

“The most important difference from conventional hacking is that the fraudsters do not need to log into the online banking computers - they simply ride on the existing and authenticated session, much as a child might slip in unnoticed through a turnstile at a sports event, train station, etc,” he added.

The Trojan is capable of performing different actions on targeted Websites, such as logging GET and POST requests, grabbing full pages, ending connections and injecting data into pages, Klein continued.

“All logged requests/grabbed pages are sent to the C&C (command and control) server in real time, allowing fraudsters to perform session hijacks, also in real time, but hidden from the legitimate user of the online bank account,” he blogged. “By tapping the session ID token - which banks use to identify a user's online banking session - the fraudsters can electronically impersonate the legitimate user and complete a range of banking operations.”

The company said it is not aware of any arrests tied to the malware, and would not identify any of the banks that were targeted. The Trojan is believed to be spreading through drive-by attacks, but may be propagating through other methods as well, the firm told eWEEK.

“The most interesting aspect of this malware is that it appears to be a work in progress, as we have seen differences in hooked functions in recent days and weeks, as well as the way the Command & Control...protocols operate,” Klein blogged. “We believe that these functions and protocols will continue to evolve in the near future, and that our analysis of the malware's functionality may not be 100 per cent complete as the code writers continue to refine it.”