Researchers have uncovered a new variant on the Zeus financial malware, which looks to recruit users as money mules to process cybercrime transactions.
According to a report from security vendor Trusteer, new variants on the malware detect when a user is trying to access popular jobs site CareerBuilder and injects code into local HTML files.
First detected as a financial malware tool, the Zeus trojan installs itself on infected PCs and functions by injecting code into otherwise legitimate HTML files. The malware is set up to detect when a user is accessing a number of popular sites and to harvest account details or ask for additional personal information. The technique allows Zeus to covertly perform attacks without the need to compromise any of the actual host servers or sites themselves.
In the case of CareerBuilder, researchers have found that Zeus injects code claiming to be job offer links. Users clicking on the injected links are then taken to a third-party site, which attempts to lure users in with jobs such as mystery shopper positions.
In reality, however, experts say users are being recruited as money mules for an organised cybercrime operation. Often operating without any knowledge of wrongdoing, money mules are commonly used by malware operators to receive payments from compromised accounts then resend the money as a wire transfer or by other means of laundering.
Trusteer said in its report: “While HTML injection is typically used for adding data fields or to present bogus messages, in this case we witnessed a rare usage that attempts to divert the victim to a fake job offering.
“Because this redirection occurs when the victim is actively pursuing a job, in this case with CareerBuilder, the victim is more likely to believe the redirection is to a legitimate job opportunity.”
Because neither the CareerBuilder site itself nor any servers have been compromised, users not infected with Zeus are not in danger from the attack. Experts advise users to guard against Zeus and other malware attacks by keeping system software, browser plugins and antivirus software patched and updated.