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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.
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Analysis of Smoke Loader in New Tsunami Campaign
Fake Japanese Meteorological Agency tsunami warning emails delivered Smoke Loader and AzoRult malware to steal credentials from targets in Japan.
A fake tsunami warning email impersonating Japan's Meteorological Agency asked recipients to click a link on a registered fake agency domain, delivering the commodity loader Smoke Loader to targets in Japan. Smoke Loader, active since 2011, is modular, and its payloads have included banking trojans, ransomware, cryptominers, password stealers, and PoS malware; the campaign later also deployed AzoRult. New samples add junk-jump obfuscation, encrypted network traffic and payload files, a unique machine ID used for tracking and encryption, and PROPagate injection into explorer.exe, with persistence via a Startup folder shortcut and RC4-encrypted C2 communication.
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SloppyRAT: A New Tool For Ransomware Attacks
Zscaler details SloppyRAT, a new DLL backdoor delivered via ClickFix lures that stages CastleLoader and CastleRAT ahead of ransomware attacks.
Zscaler ThreatLabz analyzed SloppyRAT, a DLL-based backdoor distributed via ClickFix lures that abuses finger.exe over TCP port 79 to download a batch script. The malware copies curl.exe to download IronPython 3.4.2 from GitHub and executes zlib-compressed Base64-encoded Python to deploy CastleLoader and CastleRAT, then reflectively loads SloppyRAT in memory. It hinders analysis using XOR stack-string obfuscation, a modified affine cipher with modulus 127, and 13 runtime-decrypted code blocks, while communicating with C2 over a reverse SOCKS channel.
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