Silver Fox uses new ABCDoor backdoor to target organisations in Russia and India


In December 2025, Kaspersky researchers detected a wave of malicious emails designed to look like official correspondence from the Indian tax service. A few weeks later, in January 2026, a similar campaign began targeting Russian organizations.

Kaspersky have attributed this activity to the Silver Fox threat group. Both waves followed a nearly identical structure: phishing emails were styled as official notices regarding tax audits or prompted users to download an archive containing a “list of tax violations”. Inside the archive was a modified Rust-based loader pulled from a public repository. This loader would download and execute the well-known ValleyRAT backdoor.

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Source: Kaspersky


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