A new malware strain called ValleyRAT is being deployed among large organizations around the world, researchers have warned.

Cybersecurity experts from Proofpoint published a report alleging that Chinese businesses on the mainland, but also other firms elsewhere, are being targeted by multiple new malware strains, possibly used by more than one new threat actor.

Among those is a new tool called ValleyRAT: “The campaigns distributing this malware were conducted in Chinese, and, following the trend of other Chinese malware campaigns, the majority used invoice themes related to various Chinese businesses,” the researchers said, stating that they saw multiple campaigns distributing this particular malware. 

RAT-infested emails

ValleyRAT was first spotted in March 2023, Proofpoint further stated, and while it's probably the most interesting one, it’s hardly the only variant being deployed. The researchers also spotted Sainbox (a variant of the infamous Gh0stRAT), as well as Purple Fox. With the latter, the attackers mostly went after Japanese targets:

“While historic activity aligns with what Proofpoint considers Chinese-themed, it is rarely observed in our threat data,” the researchers said when discussing Purple Fox. “Notably, one observed campaign used Japanese-language invoice themes targeting organizations in Japan to deliver zipped attachments that led to installation, while others used Chinese language invoice themed messages with URLs.”

So far, Proofpoint says it identified more than two dozen of these campaigns. In them, the attackers would impersonate major corporations and reach out to their employees via email, in an attempt to get them to download and run some of the abovementioned RATs. 

While the evidence seems inconclusive when it comes to the attackers’ identities, the researchers speculate that this could be the work of multiple groups, which most likely share valuable resources. They base these conclusions on the fact that “some activity clusters do overlap.”

The motives of the attackers are also unknown at this time.

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