Silver Fox's Tax-Themed Phishing Campaign Unveils New ABCDoor Malware
In December 2025, the China-backed threat group Silver Fox initiated a phishing campaign targeting organizations in India and Russia. The attackers sent emails impersonating tax authorities, prompting recipients to download archives purportedly containing lists of tax violations. These archives contained a modified Rust-based loader that deployed the known ValleyRAT backdoor and a previously undocumented Python-based backdoor named ABCDoor. Between early January and early February 2026, over 1,600 such malicious emails were recorded, affecting sectors including industrial, consulting, retail, and transportation. ([darkreading.com](https://www.darkreading.com/endpoint-security/silver-fox-tax-themed-attacks-india-russia?utm_source=openai)) This incident underscores the evolving tactics of APT groups, particularly their use of sophisticated social engineering techniques and novel malware to infiltrate organizations. The discovery of ABCDoor highlights the continuous development of custom tools by threat actors to evade detection and maintain persistence. ([darkreading.com](https://www.darkreading.com/endpoint-security/silver-fox-tax-themed-attacks-india-russia?utm_source=openai))
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