Proofpoint Sounds Warning on Vega Stealer Targeted Data Theft Campaign

A low-volume data-stealing campaign with the potential to get much bigger has begun targeting retail and manufacturing companies and also a select list of marketing, advertising, and public relations firms.

Email security vendor Proofpoint says it has observed and blocked new malware called Vega Stealer that is being used in the campaign to steal saved credentials, credit card data, and profile information in the Chrome and Firefox browsers. The malware is also being used to steal other sensitive data from infected computers.

Vega appears to be a somewhat stripped-down variant of August Stealer, a malware that a threat actor dubbed TA530 used in a highly personalized data-stealing campaign in 2016 aimed at managerial and customer service staff at retail companies.

As with the August Stealer campaign, the new campaign involving Vega Stealer is notable for how targeted it is. Proofpoint says it has observed emails with subjects like "Online store developer required" being sent to what it described as a "narrow set" of companies in the targeted industries.

The emails have contained a rogue attachment called "brief.doc" containing macros that download Vega Stealer. In addition to individuals, the threat actor has been sending emails with the malicious attachment to distribution lists such as "info@" and "publicaffairs@" in an apparent bid to multiply the number of potential victims at the targeted domains.

Kevin Epstein, vice president of threat research at Proofpoint, says the motivations behind the threat actor's targeting are presently unclear. "At this time, we cannot speculate on potential motivations," he says. Campaigns of this size are often either a test or a targeted effort. What organizations need to keep in mind is that Vega Stealer is capable of stealing a wide variety of data stored by Web browsers and on infected systems.

Vega Stealer in its present form is not particularly sophisticated and does not employ any packing or obfuscation methods to evade detection. The malware is designed to steal passwords, cookies, profile data, and saved credit card information from browsers. It can also search an infected computer's desktop and subdirectories for Word documents, spreadsheets, and PDF files. The malware communicates with a hard-coded remote command and control (C&C) server to which it also sends any stolen data.

What makes Vega Stealer somewhat problematic is its lineage, according to Proofpoint. Vega Stealer appears to be a modification of the considerably more widely distributed August Stealer and is being distributed by a threat actor linked to Ursnif, a somewhat notorious banking Trojan.

"August Stealer has become a fairly common threat, and Vega is a descendent of this malware," Epstein says. "It also appears that the actor distributing Vega regularly distributes the Ursnif banking Trojan, which often downloads secondary payloads such as Nymaim, Gootkit, or IcedID," he says. All of these are well-established malware families that continue to be under active development.

Organizations in targeted sectors need to keep an eye out for Vega Stealer. Though the malware is not especially sophisticated in its current form, it has the potential to become a bigger threat in future. "Although Vega does not appear to be as robust yet as August Stealer, the potential for information and credential theft for unprotected organizations is high, especially if we begin to see more widespread distribution," Epstein says.

"Email gateway protection, network protection to detect C&C communication and data exfiltration, and endpoint protection all contribute to keeping organizations safe" from threats like these he says.

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