fargo

[Content by Gemini 2.5]

Fargo (“.FARGO”) Ransomware – Community Resource Sheet

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed extension: .FARGO (upper-case)
  • Renaming convention:
    – File-name portion is left intact, the original extension is simply suffixed with “.FARGO”
    – Example: Project.xlsx → Project.xlsx.FARGO
    – No e-mail address, random GUID, or campaign ID is placed in the name (noisy/clean compared with Dharma variants)
    – Volume root and every traversed folder receive the note RECOVER-FILES.txt

2. Detection & Outbreak Timeline

  • First public samples: late August 2021 (MalwareHunterTeam tweet, ID-Ransomware hits)
  • Consistent upload spike: September 2021 → present – waves roughly every 4–6 weeks
  • Status: still an active, regularly re-packed affiliate of the “TargetCompany” (MedusaLocker) RaaS

3. Primary Attack Vectors

  • Exploitation of un-patched MS-SQL servers (public 1433 or tunneled 1433/3389) – brute sa + xp_cmdshell or sqlps.exe payload download
  • Compromised RDP / VPN credentials (often bought on Russian marketplaces). Attackers manually drop the loader
  • Lateral movement via SMB; disables RDP NLA and creates new local users (“sysadm”, “mssql_backup”, etc.)
  • Occasional phishing ZIP/ISO containing HTA → Cobalt-Strike → Fargo dropper, but SQL/RDP remain dominant
  • No current evidence of worm-like SMB exploit (EternalBlue, BlueKeep); propagation is post-compromise, manual

Remediation & Recovery Strategies

1. Prevention

  1. Patch externally facing services – especially MS-SQL, MySQL, and any app-server listening on 1433
  2. Disable xp_cmdshell, require Windows/SQL auth in “Windows-Auth-only” mode, strong sa password (>25 char)
  3. VPN / RDS hardening: MFA, account lock-out, restricted source IPs, NLA enabled, disable RDP port 3389 exposure
  4. Network segmentation & SMB egress blocking; use LAPS for local admin passwords
  5. Application whitelisting (MS Defender ASR rules, WDAC) – blocks living-off-the-land binaries (powershell download, ftp, certutil) often used by dropper
  6. 3-2-1-1 backup regime (3 copies, 2 media, 1 off-site, 1 offline/immutable) – only proven mitigation once encryption has occurred

2. Removal / Incident-Cleanup Workflow

  1. Physically isolate infected machine(s) – pull Ethernet / Wi-Fi; leave power ON (memory forensics if required)
  2. Collect artefacts before wiping:
  • ransom note (RECOVER-FILES.txt)
  • sample (*.exe usually in %TEMP%, C:\Users\Public, C:\Windows\Temp or dropped as mssql_backup.exe)
  • encrypted canary file for later ID
  1. Kill malicious processes – typical names: mssql_backup.exe, svchost.com, svch0st.exe (check WMI/SC query)
  2. Delete scheduled tasks / autostart entries created by the attacker (schtasks /query /fo csv | findstr “backup”)
  3. Remove attacker accounts & RDP hijack artefacts (net user, regkeys under HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp)
  4. Apply OS & SQL CUs, reset ALL admin passwords, re-image if possible for cleanliness (Fargo plants several secondary payloads)
  5. Run AV/EDR full scan; most engines detect as Ransom:Win32/MedusaLocker, Ransom.Win32.FARGO.A, Trojan-Ransom.Win32.Fargo.*

3. File Decryption & Recovery

  • No free decryptor exists. Fargo uses Salsa20 for file data + RSA-2048 for the Salsa key; keys are generated per machine and sent to C2 before the local copy is wiped
  • Do NOT pay unless business-critical data has absolutely no backups – payments between 2.5-5 BTC have been demanded; there is no guarantee of working decryptor, and you finance the next wave
  • Re-build system from known-good media; restore files ONLY from offline/immutable backup after re-scanning backup repository – Fargo has been observed lying dormant up to 14 days to encrypt backups

4. Essential Tools / Patches

  • MS SQL: apply CVE-2021-1636 fix + latest CU (CU12+ for SQL 2019, CU25+ for SQL 2017)
  • MS Defender / Microsoft Safety Scanner – full update, enable “Block Office apps from creating executable content” ASR rule
  • Sysinternals: Autoruns, Process Explorer, PSTools – clean rogue entries
  • Kaspersky AVZ, ESET RESCOM, or Malwarebytes TechBench boot kit if the OS is un-bootable
  • KeePass or similar PAM solution for eliminating password reuse across SQL/RDP vectors

5. Other Critical Information

  • Persistence oddity: Fargo creates a secondary service named FargooService (double ‘o’) – easy live-hunt pivot
  • Extension confusion: do not confuse with FargoCounty Ransomware (2020) or a 2022 Dharma off-shoot that appended “.FARGO2” – different decryptor requests; check the ransom note text (“TARGET COMPANY” string vs “write us at e-mail …”)
  • Data exfiltration (still rare for Fargo) occurs in newer affiliates – watch for mssql_backup.zip staged in C:\Zips\ before encryption; treat incidents as potential data-breach until proven otherwise
  • Sector focus: attacks concentrate on small-to-mid manufacturing, dental/medical clinics, and regional MSPs that expose SQL for LOB apps – ensure vertical-centric threat hunting rules are enabled

Bottom line: If you see .FARGO, power down affected boxes, rebuild from scratch, and restore from a backup that predates the earliest suspicious SQL/RDP login. Without offline backups, decryption is currently impossible; concentrate on containment, evidence preservation, and hardening rather than funding the criminals.