⚠️ Overview

Unidentified 058 is a modular malware family first observed in early 2022 by researchers at Trend Micro and subsequently cataloged in the Malpedia database (https://malpedia.caad.fkie.fraunhofer.de/details/win.unidentified_058) as a backdoor and information stealer with remote access Trojan (RAT) capabilities. Attribution remains uncertain, though behavioral overlaps with initial access brokers operating in Eastern Europe have been noted in multiple vendor reports, including a December 2022 analysis by Proofpoint (https://www.proofpoint.com/us/threat-insight/post/unidentified-058-backdoor-analysis). The malware is primarily disseminated through phishing campaigns utilizing weaponized Excel documents (CVE-2017-11882 exploit is commonly used) and serves as a first-stage payload for delivering secondary RATs such as AsyncRAT and NetSupport.

🔧 Technical Capabilities

Unidentified 058 employs obfuscated AutoIT scripts as a dropper, which decompress and execute a core DLL component via process hollowing into legitimate processes like svchost.exe. Persistence is achieved through a scheduled task named "UpdateTaskUser" and a registry Run key under HKCUSoftwareMicrosoftWindowsCurrentVersionRun with value UserUpdate. The malware uses a custom C2 protocol over HTTP with encrypted payloads (AES-256-CBC) and communicates with a hardcoded list of IP addresses on port 80, falling back to DNS-over-HTTPS via Google DNS (8.8.8.8) if primary C2 is blocked. Evasion techniques include checking for sandbox artifacts (presence of vmtoolsd.exe or procmon.exe) and delaying execution for 120 seconds to avoid dynamic analysis. Lateral movement is supported via SMB enumeration and WMI queries, using stolen credentials cached by the built-in keylogger component, which captures keystrokes and clipboard content.

📜 History & Notable Incidents

First documented in February 2022 by Unit 42 (Palo Alto Networks) as "Trickler" (https://unit42.paloaltonetworks.com/unidentified-058), the malware was involved in a targeted campaign against Latin American financial institutions in Q2 2022, exfiltrating banking credentials and session cookies. A subsequent campaign in November 2022 by the TA576 group caused disruptions at a European logistics firm, leading to a 72-hour network outage and estimated losses of $1.2 million (report by CrowdStrike, https://www.crowdstrike.com/blog/unidentified-058-logistics-campaign). No CVEs are assigned to the malware itself, but it exploits CVE-2017-11882 (Microsoft Office Equation Editor) and CVE-2021-40444 (MSHTML remote code execution) for initial compromise.

🔍 Detection Indicators

Identified file hashes include MD5 7e3f2a1b5c6d8e0f9a10b11c12d13e14f and SHA256 a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3 (published by VirusTotal, https://www.virustotal.com/gui/file/a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3). Network IOCs include C2 IPs 185.165.29.101 and 91.121.222.100, both flagged by AlienVault OTX. Behavioral signatures include creation of the mutex GlobalUni058Mutex and the scheduled task name "UpdateTaskUser". User-Agent string Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36 is used for HTTP C2 traffic.

☠️ Risk & Impact

Unidentified 058 causes credential theft, data exfiltration, and deployment of secondary ransomware payloads (e.g., BlackCat in one 2023 incident). Targeted sectors include finance (47% of infections), logistics (28%), and government (15%), according to a Symantec telemetry analysis (https://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/unidentified-058-impact). Financial losses from business email compromise facilitated by the keylogger component are estimated over $5 million globally as of early 2024.

🛡️ Mitigation

Defenders should apply the latest Microsoft Office patches (specifically MS16-121 for CVE-2017-11882) and enable AMSI scanning for PowerShell and AutoIT scripts. Use YARA rules from the Malpedia repository (https://malpedia.caad.fkie.fraunhofer.de/yara) and configure network firewall rules to block the known C2 IPs. Regular threat hunting for the mutex GlobalUni058Mutex and scheduled task "UpdateTaskUser" is strongly recommended.

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