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The Gopher in the Room: Analysis of GoLang Malware in the Wild
Unit 42 analysis of 10,700 Go-compiled malware samples shows steady growth in the wild, with 92% targeting Windows and top families including Veil, GoBot2, and HERCULES.
Unit 42 collected roughly 10,700 unique Go-compiled malware samples and found that Go usage by malware developers has steadily risen in recent months. About 92% of samples targeted Windows and 75% were attributed to known families, led by Veil, GoBot2, and HERCULES. The most prevalent groupings were penetration testing tools, remote access Trojans, and backdoors. Statically linked Go binaries average 4.65MB, which can complicate phishing delivery but sometimes causes antivirus products to skip or fail scanning.
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Redtail Payload Analysis [Guest Diary], (Wed, Sep 9th)
SANS guest analyst detonated a RedTail Linux sample from a DShield honeypot, finding process masquerading as php-fpm, monitoring-kill behavior, and a TCP listener.
A DShield honeypot captured multi-architecture RedTail Linux executables (ARM, ARM64, i686, RISC-V, x86-64) deployed via shell scripts. Dynamic analysis of the UPX-packed, statically linked x86-64 sample (SHA-256 63be5f38...d35e) in an isolated Ubuntu 24.04 VM on Proxmox showed it renamed its process via prctl(PR_SET_NAME), killed a filesystem-monitoring process, and opened a TCP listening socket while surviving processes posed as php-fpm or PostgreSQL-like workers. Differential memory images pre- and post-execution were captured from the hypervisor for forensics.
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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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CryptoBit: Another Ransomware Family Gets an Update
Palo Alto Unit 42 analyzes updated CryptoBit ransomware distributed via the Rig exploit kit, documenting IOCs, eight sample hashes, and disguise tactics from June 2016.
Unit 42 observed an updated CryptoBit ransomware variant (also tracked as CriptoBit or Mobef) delivered through the Rig exploit kit via the gate domain realstatistics.info between June 17-27, 2016. Infections targeted Windows hosts with out-of-date Flash plugins, and post-infection callbacks used fake user-agents and referrers to disguise traffic to laoismacau.com. At least eight samples were collected, and by June 27 the campaign had begun distributing other malware.
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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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Re: Retrospective by 'gpg.fail' authors
GnuPG's Werner Koch says gpg.fail samples only crash GnuPG via DER-as-printf format string in --debug x509; RCE claim remains unproven.
Werner Koch replied to the gpg.fail retrospective, noting that GnuPG versions above 2.2 produce garbled stderr or crash when the project's certificates are used with --debug x509 because DER data is passed as a printf format string. Testing the certificates from the researchers' Git repo yielded only a segfault, not demonstrated code execution. Koch states how remote code execution would be achieved is unclear and asks for a real reproducer.
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