Level 31
Sofacy’s First-Stage Malware Zebrocy Analyzed

ESET security researchers have taken a deep dive into one of the tools heavily used by the Russian threat actor Sofacy over the past couple of years.

Dubbed Zebrocy, the tool serves as a first-stage malware in attacks and is comprised of a Delphi downloader, an AutoIt downloader and a Delphi backdoor. Used in multiple attacks, the malicious program often acts as a downloader for the actor’s main backdoor, Xagent.

Also referred to as APT28, Fancy Bear, Pawn Storm, Sednit, and Strontium, and active since around 2007, the group is focused on cyber espionage and has hit government, military, and defense organizations worldwide.

Supposedly the actor behind attacks targeting the 2016 presidential election in the United States, Sofacy has been known to target Ukraine and NATO countries, and has recently switched focus to targets in Asia.

Coexisting with another Sofacy first-stage tool, Seduploader, the Zebrocy malware has been used in attacks against victims in Azerbaijan, Bosnia and Herzegovina, Egypt, Georgia, Iran, Kazakhstan, Korea, Kyrgyzstan, Russia, Saudi Arabia, Serbia, Switzerland, Tajikistan, Turkey, Turkmenistan, Ukraine, Uruguay and Zimbabwe, ESET reveals.

Zebrocy is usually delivered via emails carrying malicious attachments and users are lured into opening them. These are either Microsoft Office documents that deliver the payload via VBA macros, exploits, or Dynamic Data Exchange (DDE), or archives containing executables with an icon and a document-like filename.

Once the malicious attachment is executed, the first stage of the Zebrocy family is delivered: a Delphi downloader (in some attacks the AutoIt stage was used directly). The downloader is usually masked using document or Windows library icons and some samples are packed with UPX.
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