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Muhstik Botnet Attacks Tomato Routers to Harvest New IoT Devices
Unit 42 found a Muhstik botnet variant brute-forcing Tomato router web authentication to harvest IoT devices for crypto mining and DDoS attacks.
Palo Alto Networks Unit 42 researchers in December 2019 identified a new Muhstik botnet variant scanning Tomato routers on TCP 8080 and brute-forcing default admin credentials, targeting roughly 4,600 exposed devices found via Shodan. The variant also scans WordPress and Webuzo installations and exploits the Oracle WebLogic deserialization flaw CVE-2019-2725 for unauthenticated remote code execution. Muhstik, active since March 2018, self-propagates like a worm and typically monetizes infections through cryptocurrency mining and DDoS attacks controlled via an IRC C2 channel.
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Eleethub: A Cryptocurrency Mining Botnet with Rootkit for Self
Unit 42 uncovered Eleethub, a Perl-based Bitcoin mining botnet using a crafted rootkit and libprocesshider to evade detection, still under development with few infections.
Unit 42 discovered an under-development Perl Shellbot campaign that mines Bitcoin using xmrig and emech while evading detection via a rootkit that replaces the ps tool and the LD_PRELOAD-based libprocesshider.so library. Infected devices download a malicious shell script, connect to IRC-based C2 at eleethub.com and the UnderNet network, and can receive commands for UDP/TCP floods, port scans, and HTTP attacks. The botnet can affect Unix systems and Windows 10 hosts running a Linux subsystem, and its operators use the 'Los Zetas' branding, though they are unlikely to be the Mexican drug cartel. Researchers found only a few compromised 'zombies' before the campaign expanded.
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Malspam Targeting Brazil Continues to Evolve
Brazilian malspam campaigns continue evolving, abusing Google URL shortener and Dropbox and using Squiblydoo plus DLL side-loading to deploy likely infostealing botnet malware.
A June 2017 Brazilian malspam campaign spoofed IPTU tax notification emails, using the recipient's address as the sender, and abused Google's URL shortener and Dropbox to deliver a zip containing a malicious Windows shortcut (.lnk) file. The LNK used the Squiblydoo technique (regsvr32.exe) to download and execute a scriptlet with elevated privileges, retrieving a signed G-Buster Browser Defense executable alongside a malicious fltLib.dll loaded via side-loading, likely an information-stealing botnet. Post-infection HTTP traffic exposed over 400 infected Windows hosts, mostly in Brazil, with 2,132 Banload-tagged samples observed in the first half of 2017.
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Upatre Continued to Evolve with new Anti
Unit 42 analyzes an undocumented Upatre downloader variant with VM detection via process hashing, packed code, disabled Windows defenses and Namecoin .bit C2 domains.
Unit 42 analyzed an Upatre downloader variant compiled in December 2016 that went largely undetected by automated systems, featuring heavy code flow obscuration, on-demand decryption of network communications, and novel virtual machine detection. The sample enumerates running processes, computes CRC32 hashes XORed with a hard-coded key, and sleeps if analysis-related processes such as vmtoolsd.exe or python.exe are found. It masquerades with Google Chrome icons, disables Windows Defender, Firewall and other security services, injects code into msiexec.exe, and resolves .bit Namecoin domains like bookreader[.]bit via hardcoded OpenNIC DNS servers over TCP.
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