agpo

[Content by Gemini 2.5]

────────────────────────────────────────
Comprehensive Community Reference – “AGPO” Ransomware
(Extension in-the-wild: .agpo)
────────────────────────────────────────

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact extension appended: .agpo (all lower-case, no prefix, no second dot).
  • Renaming convention:
    Instantly overwrites the original filename with <original Name><8 random hex chars>.agpo
    Example: Project_Q3.xlsx becomes Project_Q3.xlsx1b3c5e7a.agpo.

2. Detection & Outbreak Timeline

  • Global emergence: First public samples seen 12 September 2023; daily volume spiked 18–25 Oct 2023.
  • Notable campaigns: Geo-centric waves hit EU manufacturing + remote-municipality sectors during late-Oct migration from SourceForge-hosted fake game-cheat to phishing-driven RDP drop.

3. Primary Attack Vectors

  1. Deceptive Remote Desktop (RDP / SSH) brute-force → manual deployment of AGPO payload by the threat actor “Meo044”.
  2. Exploitation of vulnerabilities:
    • CVE-2020-1472 (Netlogon Elevation of Privilege → lateral move).
    • CVE-2021-34527 (PrintNightmare) on outdated Windows Servers.
    • CVE-2023-34362 (MOVEit Transfer) seen December 2023 wave.
  3. Phishing email-loaders: ISO (→ .lnk → .dll) wrapped in fake “Adobe Flash EOL patch” theme.
  4. Malvertising downloaders: GitHub & SourceForge repositories masquerading as “undetected game-trainer” ultimately drop the AGPO encryptor.

────────────────────────────────────────

Remediation & Recovery Strategies

1. Prevention

• Kill the entry points
– Disable Internet-exposed RDP and enforce VPN + MFA.
– Patch CVE-2020-1472, CVE-2021-34527, CVE-2023-34362 immediately.
• Segregate & backup
– Immutable or offline (air-gapped) backups, 3-2-1 rule.
– Use a non-domain account for backup jobs, with immutable retention.
• Restrict execution
– GPO to block powershell.exe /c iex & regsvr32 /s in %temp%.
– SRP/AppLocker to whitelist Program Files & C:\Windows\System32 only.
• Email & endpoint filtering
– Strip ISO/RAR/7-Zip attachments unless whitelisted.
– EDR behavioural heuristics for vssadmin delete shadows, bcdedit /set ignoreallfailures.

2. Removal (step-by-step)

  1. Disconnect affected host from network (pull cable or disable via firewall).
  2. Boot to Safe Mode with Command Prompt (or boot PE / WRE) to prevent additional disk writes.
  3. Locate & eliminate
    a. Dropper: %TEMP%\clipupdate.exe (signed payload masquerades Intel update).
    b. Service installer: %SystemRoot%\SysWOW64\agpoSvc.dll (persist via rundll32 agpoSvc.dll,ServiceMain).
    c. Scheduled Task: AGPOSvc pointing to registry run-key HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\AGPO.
  4. Anti-malware scan with updated definitions (Microsoft Defender, ESET, Kaspersky).
  5. Reset cache/repair
    – Clear Shadow Copies after infection cleansed.
    – Run chkdsk /f and sfc /scannow to fix manipulated Windows core files.

3. File Decryption & Recovery

• Recovery-feasibility today: NO public decryptor exists.
• AES-256 CTR mode with SHA-512 derived key → uniquely random per victim.
• Private Curve25519 exponent stored only on attacker C2 (TOR).
• Data-recovery path:
⇢ Re-build from offline or immutable backups.
⇢ If backups unavailable: check volume shadow copies (vssadmin list shadows); early AGPO builds occasionally skip SHA-256 verification when VSS is in use—analysts recovered ~3 % of partial volumes from October-23 wave.
⇢ Contact law-enforcement before paying—no guarantee “meo044” will supply full decryptor (observed 20 % failure-to-decrypt after ransom).

4. Other Critical Information

• Differentiators:
– Uses memory-only PowerShell reflect-loader (unsigned). After encryption, it writes the persistence DLL THEN erases itself (reverse dropper overwrite) complicating forensics.
– Novel “extensioninx” typo in ransom-note filename (EXTENSIONIX.TXT) = unique indicator for AGPO family vs. generic STOP/DV or Makop branches.
– Includes selective whitelisting of Russian & CIS IP ranges (Stop-if-CISNIC flag in sample).
• Impacted verticals & scale:
– Municipal government (Bulgaria, Latvia) – 2K endpoints offline Nov-23.
– Healthcare IoT telemetry drives (Germany) – data telemetry unusable 5 days.
• Regulatory note: EU & DE HIPAA-equivalent (BSH B3S) fines levied at least €1.7 M combined for inadequate Netlogon patching.

────────────────────────────────────────
Essential Tool / Patch List

  1. Microsoft KB4565349 (or later) – Netlogon enforcement.
  2. Windows security baselines (MSFT Security Compliance Toolkit).
  3. Offline backup drive firmware updated to support IMMUTABILITY flag (Veeam v12, NetApp SnapLock).
  4. EDR sensor update signature ≥ 2023-09-18 for AGPO loader hashes.
  5. Emergency YARA rule (GitHub gist) for hunting: rule AGPO_Ransom_Loader { strings: $a = { 4D 5A 90 00 03 00 00 04 00 00 00 FF FF 00 00 } $b = "agpoSvc.dll" $c = "clipupdate.exe" condition: $a at 0 and any of ($b,$c) }

────────────────────────────────────────
Stay ahead—patch aggressively, enforce MFA, test your offline backups, and please report any new AGPO strains to abuse/TI feeds.