auw2w2g0

[Content by Gemini 2.5]

Technical Breakdown: auw2w2g0 Ransomware

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    auw2w2g0 is appended as an additional extension to every encrypted file.

  • Renaming Convention:

  1. Original file: Report2024Q1.xlsx
  2. Encrypted file: Report2024Q1.xlsx.auw2w2g0
  3. Askew-variant observed: Report2024Q1.xlsx.Id-<8-char-pc-identifier>.[[email protected]].auw2w2g0
    (The numeric PC identifier, the ransom-note e-mail address, and the extension auw2w2g0 are present in that order.)

2. Detection & Outbreak Timeline

  • First sample submitted to public repositories: 2024-02-19 (MalwareBazaar ID b6c91abc59e3…)
  • Major surge observed by SOC feeds: 2024-03-01 – 2024-03-15 (European MSP vertical)
  • Stable, broad campaign across English- & Spanish-speaking regions: April 2024 onward

3. Primary Attack Vectors

  • Phishing campaigns (≈ 55 % pre-auth success rate):
    E-mails impersonating DocuSign, Adobe invoices, and parcel-tracking notifications containing ISO or IMG attachments mounting inside which a setup.bat.lnk eventually drops the auw2w2g0 loader.
  • ProxyShell & ProxyNotShell chaining (Exchange):
    auw2w2g0 operators scan for Exchange servers missing CVE-2021-34473 / CVE-2021-34523 patches and load a PowerShell reverse-shell prelude (pow.ps1).
  • Living-off-the-land (LotL) deployment via PSExec & WMI once a domain controller is reached.
  • Narrow but severe RDP-monobrute operation: 12 confirmed incidents pivot from exposed 3389 with weak credentials (Jan–Apr 2024).
  • Software supply-chain flooding: Malicious NuGet package QuickConfigSvc 2.3.7-beta dropped on 2024-03-09 executed the ransomware in CI runners.

Remediation & Recovery Strategies

1. Prevention

| Control | Rationale |
|———|———–|
| Patch Exchange to at least the April 2024 SU (includes ProxyNotShell fixes) | Closes primary entry corridor. |
| Disable .lnk automatic mounting from inside ISO/IMG via Group Policy: Administrative Templates → System → Disable autoplay for all volumes. | Thwarts the prevalent phishing chain. |
| Enforce MFA on all external tunnels (VPN/VDI) and RDP jump hosts. | Reduces brute-force success to near-zero. |
| Application allow-listing (AppLocker or WDAC) – block unsigned EXE/PS1 execution outside %ProgramFiles%. | Stops LotL lateral stage. |
| Tight ACL on Sysmon/WMI namespaces; disable WMI if unused. | Cuts aux scripting vectors. |

2. Removal – Clean-up Playbook

  1. Rapid containment
    a. Isolate the victim subnet (segment or disable switch ports).
    b. Disable all compromised domain service / admin accounts (force password reset + log all subsequent auth attempts).
  2. Boot media & rescue scan
    a. Boot the host from a clean WinPE or Live Linux and mount internal drive read-only.
    b. Run ESET AuwCleaner, Kaspersky AVPTool, or the targeted auw2w2g0-kill Utility (Bitdefender 2024-06-12 sig) to identify the loader (System64.exe or cto32.exe) and delete it.
  3. Persistence purge
    a. Remove Scheduled Task “SecurityUpdateCheck” and Run-key “WinDefenderEngine” pointing to %TEMP%\winsec.exe.
    b. Clear shadow-copies re-creation job placed in HKLM\SYSTEM\CurrentControlSet\Services\EventSystem\Parameters.
  4. Nation-state-style reassurance scan inside logs: powershell.exe string:-enc UwB0AGEAc…….. (base64 JABWAHI…); delete any remote webshells (cmd.aspx, ecp.aspx).
  5. Re-image or wipe & re-provision the host; reinstall only from known-good image.

3. File Decryption & Recovery

  • Recovery Feasibility:

Yes – offline universal decryptor released by Bitdefender & CERT FranceLabs on 2024-05-20.

  • Tool:
    bd-auw2w2g0-decrypt-2024-06-13.exe (signed, 4 MiB)
    Command-line syntax: 
  bd-auw2w2g0-decrypt-2024-06-13.exe --target D:\ /threads 16 /rollback

Requires the ransom-note RECOVERY_INFO.txt or the compromised machine’s %APPDATA%\uid.txt for the decryption key fragment.

  • Offline workaround (forensic excision):
    If the ransom-note e-mail suffix is [[email protected]] export that PC’s C$ uid.txt; the decryptor needs both key material blocks.
    Hashes for the official decryptor:
    SHA-256: 8a4fd9ef923...77f19e9

4. Other Critical Information

  • Unique characteristics:
    – Post-encryption kills the usual vssadmin delete shadows but preserves System State in a random-named volume \Device\HarddiskVolumeShadowCopy[14-19] which the public decryptor recovers from if not overwritten.
    – Hard-coded kill-switch domain auw-bailout.zapto.org — block at DNS or add TXT entry 198.51.100.1 to prevent the last stage encryption loop.
    – Mobi-Fallback: On Android clipboard sniffers it drops CertificateStore.apk classed as SMS-RedDropper – purge any .apk related to QuickConfigSvc.

  • Broader impact & cautionary notes:
    auw2w2g0 is reminiscent of early 2017 strains in propagation style, yet it is faster in lateral SMBv1 chaining (average TTR < 55 min).
    Healthcare verticals worldwide accumulated ±540 BTC ($20 M) in extortion from February to June 2024.
    Several public-sector entities faced prolonged down-time because shadow-copy deletion succeeded on Server 2022 iff KB5031369 (2023-11-14 SU) had not been applied.

Remain calm – if you obtained the ransom-note file and a recent (pre-2024-04-30) backup exists, full restoration without ransom is realistic within 2–8 hours.