Cybersecurity researchers have unearthed new malware threats manufactured to exploit steganography methodologies. Worok seems to be a complex cyber-espionage operation whose individual stages are still unknown. The campaign's final stage, however, has been identified by two cybersecurity firms.
Worok employs multi-stage malware created to siphon data and target high-profile victims, using steganography ways to conceal parts of the payloads in a plain PNG image file. The new malware was first uncovered by ESET in September.
The researchers described Worok as a new cyber spying group that employs undocumented tools, including a steganography methodology designed to exfiltrate a malicious payload from a plain PNG image file.
The cyber espionage group targeted high-profile victims like government agencies, particularly in the Middle East, Southeast Asia, and South Africa. ESET's knowledge of the trouble's attack chain was limited, but the latest report from Avast has provided fresh details regarding this malicious campaign.
According to the Czech security firm, Worok employs a complex multistage design to conceal its activities. The hackers employ sideloading to execute the CLRLoader malware which, in turn, implements the PNGLoader DLL, capable of reading obfuscated code masking in PNG files.
That code translates to DropBoxControl, a custom .NET C# infostealer that abuses Dropbox file hosting for communication and data theft. The info stealer can support multiple commands, including running cmd /c, launching an executable, downloading and uploading data, deleting and renaming files, capturing file information, spy network communications, and extracting metadata.
While researchers are still trying to put all the pieces together, the latest report from Avast confirms that Worok is a custom operation manufactured to siphon data, spy, and target high- victims in specific parts of the globe.
“The key finding of this research is the interception of the PNG files, as predicted by ESET. The stenographically embedded C# payload (DropBoxControl) confirms Worok as the cyberespionage group. They steal data via the DropBox account registered on active Google emails,” Researchers at AVAST explained. “The prevalence of Worok’s tools in the wild is low, so it can indicate that the toolset is an APT project focusing on high-profile entities in private and public sectors in Asia, Africa, and North America.”