Qakbot, aka QBot, QuackBot and Pinkslipbot, is a banking trojan that was first spotted in the wild 17 years ago, in 2007. Since its toddler days, it’s become one of the most prevalent banking trojans found around the world.
Though its main purpose is info-swiping – e.g., ripping off logins, passwords and more – the malware has picked up myriad other nasty habits: spying on financial operations, spreading and installing ransomware, keystroke logging, a backdoor functionality, and smooth moves to evade detection, including detecting its environment, self-updating, and cyptor/packer updates. It also fights back against being analyzed and debugged, be it by experts or automated tools.
Sophos labs analyzed a campaign in which the Qakbot botnet inserted malicious messages into existing email threads: messages that included a short sentence and a link to download a zip file containing a malicious Excel spreadsheet. The message asked the targeted user to “enable content” to activate the infection chain.
Once the botnet infected a target, it scanned them in order to get a detailed profile that it then passed on up to the C2 server.
Then, the botnet downloaded more – at least three – malicious modules.
The payloads, which were injected into browsers, took the form of dynamic link libraries (DLL) that broadened the botnet’s capabilities to include these unsavory tidbits:
A module that injects password-stealing code into webpages.
A module that performs network scans, collecting data about other machines in proximity to the infected computer.
A module that identified the addresses of a dozen SMTP (Simple Mail Transfer Protocol) email servers and then tried to connect to each one and send spam.