Cybercriminals are impersonating the Brazilian postal service in a malware campaign that combines legitimate Windows files such as Windows Management Instrumentation (WMI) and CertUtil to steal banking data.

Investigators tracked the threat to a series of email messages telling victims they’d missed a package that was to be delivered to their location. The emails contain a bogus tracking code and an embedded link to download a ZIP file.

At this point, a LNK file points to cmd.exe, which makes use of WMI, a command line utility, to execute scripts from the attackers’ command-and-control (C&C) server. At the same time, the threat actors use a copy of CertUtil that is created and stored in a temporary folder with a different name to cover their tracks.

The victim’s machine must use Portuguese as its main language for the scripts to execute, suggesting that the group behind the attack may intend to target users outside of Brazil.

Malware Campaign Evades Detection Using Windows Components

The researchers noted that while this is not the first time threat actors have leveraged components such as WMI and CertUtil, the fact that these two files were combined suggests that the group behind this campaign is experienced in evading detection.

Although WMI and CertUtil were not designed for cybercriminal purposes, this incident shows that they can be subverted, making it even more difficult for IT security teams to recognize malicious activity until it’s too late.

Adopt a Layered Approach to Data Protection

To contend with threat actors who endeavor to hide their malicious activity from security tools, organizations should adopt a layered approach to data protection. According to IBM’s “2018 Cost of a Data Breach Study,” in fact, there is a clear correlation between investing in such a strategy and successfully recovering from cyberattacks. Organizations that fully deploy security automation, for instance, experience a net total cost difference of $1.55 million compared to companies that don’t.

Source: TrendMicro