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.
Understanding Angler Exploit Kit
Unit 42 examines Angler EK operations, including rapid zero-day adoption, fileless Bedep infections, and ransomware payloads like TeslaCrypt and CryptXXX.
Unit 42 published the second part of its Angler EK analysis, covering the kit's history since 2013, its SaaS rental model, and its focus on Flash, Internet Explorer, and Silverlight exploits. Angler integrated the CVE-2015-5119 Flash zero-day from the Hacking Team leak within hours and later added exploits for CVE-2015-2419 and CVE-2016-0034 roughly a month after Microsoft patched them. Campaigns use Angler to deliver ransomware such as CryptoWall, TeslaCrypt, and CryptXXX, plus banking trojans and stealers via EITest. Since August 2014, Angler has used fileless, in-memory execution, most often for Bedep, which later downloads CryptXXX and click-fraud malware.
Researchers Use Claude to Port Pre-Auth RCE Exploit From One PLC Model to Another
Forescout used Anthropic's Claude to port a working pre-auth RCE exploit for CVE-2021-31886 between WAGO PLCs, executing ARM shellcode on live hardware.
Forescout Vedere Labs used Claude interactively to port an RCE exploit for CVE-2021-31886, a CVSS 9.8 stack buffer overflow in the Nucleus FTP server's USER command, from a WAGO 750-852 to a WAGO 750-831 PLC, running attacker-supplied ARM shellcode. The final RCE stage cost $535.74 in API usage over 8 hours 32 minutes, and a follow-up attempt to build a C2 implant permanently bricked the device. CERT@VDE lists many Nucleus V1-based WAGO models as vulnerable with no updates available; Siemens plans no Nucleus NET remediation. The work follows a joint NSA/CISA/FBI/DOE/EPA advisory warning of AI-generated exploitation scripts targeting internet-exposed Siemens S7 PLCs.
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.