By Pierluigi Paganini, Editor-in-Chief
Botnet author are increasing complexity of the malicious code they use and same time security firms are adopting more sophisticated detection methods. Between principal concerns of botmaster the need to improve capabilities of bot agents to operate silently and necessity to masquerade traffic from bots and Command & Control servers.
Focusing on this second question in the past authors of botnet malware have misused popular platform such as Google Docs, Twitter and Facebook to masquerade malicious traffic.
Researchers at TrendMicro recently detected a malware, dubbed “BKDR_VERNOT.A” that tried to exploit popular note-taking app Evernote as Command-and-Control Server to provide instructions to the bot installed on victim’s machine.
Authors of “BKDR_VERNOT.A” tried to send command to bot with Command-and-Control Server using Evernote, malicious delivered via an executable file that installs the malware as a dynamic-link library, once installed DLL is linked to a legitimate running process to remain undetected from detection systems.
The behavior of BKDR_VERNOT.A is typical of any backdoor code, it is able to receive commands such as downloading, executing, and renaming files. The malware collects information from the infected system, including OS version, timezone, user name, computer name and organization.
As is possible to note in the above picture the malicious code may have used Evernote as Command Server where to store stolen data, unfortunately the researchers haven’t had during analysis access to the account used by the agent.
“Unfortunately, during our testing, it was not able to login using the credentials embedded in the malware. This is possibly a security measure imposed by Evernote following its recent hacking issue.”
“Though this is a clever maneuver to avoid detection, this is not the first time that a legitimate service like Evernote was used as a method of evasion.”