Bisonal Malware Used in Attacks Against Russia and South Korea
Unit 42 details a Bisonal malware variant, active since 2014, targeting Russian and South Korean defense organizations via PDF-disguised spearphishing emails.
In early May, Unit 42 discovered a campaign delivering a Bisonal malware variant against at least one Russian communications security and cryptography company and one unidentified organization in South Korea. The variant, in the wild since at least 2014, introduces a new C2 cipher and rewritten networking and persistence code, with only 14 samples collected to date. Attackers spoofed Russian state corporation Rostec in spearphishing emails carrying an executable disguised with a PDF icon; the dropper decrypts an RC4-encrypted DLL and establishes persistence via a registry Run key. Bisonal has been used since 2013 against government, military, and defense targets in South Korea, Russia, Japan, and India, alongside successors Bioazih and Dexbia.
Kimwolf botnet rebuilt to survive takedowns, researchers say
Palo Alto Unit 42 reports the Kimwolf/Aisuru botnet now uses HTTP/2 Chrome-impersonation floods and Ethereum blockchain-based command resolution to survive takedowns.
Palo Alto Networks' Unit 42 says a new Kimwolf/Aisuru botnet version active since February conducts DDoS floods over HTTP/2 with full Chrome browser fingerprints, making attack traffic hard to distinguish from real users. The malware resolves command servers via the Ethereum Name Service using five shuffled Ethereum endpoints, with a Tor hidden service fallback, so authorities cannot seize a domain or serve a takedown order. The botnet, powered mostly by hijacked Android TV boxes and IoT devices, previously had servers seized and an alleged operator arrested; new C2 infrastructure traces to a single network in Saint Petersburg, Russia. It is unclear whether the same developers built the new version.