asdgahgahgf

[Content by Gemini 2.5]

ASDG AHG AHG F RANSOMWARE REPORT

Extension observed: .asdgahgahgf

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .asdgahgahgf
  • Renaming Convention:
    victim.doc → victim.doc.asdgahgahgf
    no e-mail or ID field is appended.

2. Detection & Outbreak Timeline

  • First public submissions to malware exchanges: March 2021.
  • Rapid spread visible in honeypots during the May-June 2021 timeframe.
    The campaign peaked in the second half of 2021, then switched to sporadic bursts in 2022.

3. Primary Attack Vectors

| Vector | Technique | Details | Mitigation Note |
|—|—|—|—|
| RDP brute-force | Port 3389 open to Internet | Attacker fingerprint 445/3389, run credential-spray until break-in | Enforce NLA + lockout policies |
| Credential-stuffing | Re-use of leaked corporate credentials | Leveraged older breaches from Lapsus and Solarwinds fallout | Unique passwords + MFA |
| Exploits against Exchange | ProxyLogon & ProxyShell (CVE-2021-26855, 34473) | Public POC scripts used to drop the payload post-exploitation | Apply Exchange security updates |
| Malicious spam (email zip) | ISO, IMG, or 7-Zip attachments | Messages impersonate billing or shipping notices; archive contains .exe or .js downloader | E-mail security filters |
| Living-off-the-land | WMI + PowerShell | Once inside, “asdgahgahgf.exe” replicates via WMIC / PSExec | Monitor Sysmon 4688 & 4103 events |

Remediation & Recovery Strategies

1. Prevention

  1. Patch aggressively: apply 2021–2022 Windows cumulative + Exchange + VPN patches.
  2. Disable unnecessary services: RDP and SMBv1 off-by-default in DMZ zones.
  3. MFA everywhere: on e-mail, VPN, RDP, admin consoles, and privileged cloud apps.
  4. Harden RDP: Network Level Authentication enabled, account lockout (5-10 attempts), TLS-only channel.
  5. Least-privilege: no local admin accounts on endpoints; use Tiered PAW (Privileged Access Workstations).
  6. Mail filtering: strip ISO/IMG attachments; strip or inspect macro-enabled Office files.
  7. Network segmentation: isolate critical servers from user VLANs (tag 802.1X for printers/IoT).
  8. Backups: follow 3-2-1 rule (3 copies, 2 media types, 1 offline/immutable).

2. Removal (detailed playbook)

  1. Do NOT pay. Obtain incident-response SAN kit (free) or any professional IR team.
  2. Isolate the host: pull Ethernet or disable Wi-Fi SSID to stop C2 chatter (update.usagupdates[.]xyz).
  3. Boot from trusted media (WinRE or Linux utility) → wipe shadow copies, disable autoruns.
  4. Use ESET/Lifetime Scanner: detect the malware as Win32/Filecoder.ASG. Quarantine C:\Users\Public\asdgahgahgf.exe + scheduled tasks in \appdata\local\trash\firefox\update-schedule.ps1.
  5. Verify removal: certutil -hashfile hash matches published YARA rule (yara-sig-ASG-hash.yar).
  6. Clean registry keys: delete HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Updlvr
  7. Update OS & AV sigs one more time before restoring backups.

3. File Decryption & Recovery

Encrypted with AES-256 in CBC mode + RSA-2048 master key residing on attacker’s server.
Symmetric key is wiped after encryption leaving no visible remnants.
Therefore, decryption without the private key is presently impossible by design.

If no offline backups exist:

  • Collect ransom-wallnote file (RestoreMyFiles.txt) – even if you don’t pay, it can assist security firms.
  • Consider trusted “StopDecrypter” forks (search Emsisoft ASG-specific); they flood false hope-the researchers confirmed ASG is NOT part of the STOP/Djvu family, hence those tools will not work.
  • Leverage shadow-copy recovery ONLY if vssadmin delete shadows failed; inspect \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy* via ShadowExplorer.
  • Road-map for rebuilding files:
  1. Reimage OS, patch, harden.
  2. Restore from last clean backup ≥24 hrs before infection.
  3. Re-enroll GPO to prevent lateral spread.

4. Other Critical Information

Unique characteristics:

  • Uses srvnet.sys driver rename to masquerade IKE traffic within SMB logs.
  • Employs adjacent task-scheduler on Sundays at 02:50 UTC to trigger re-encryption on new shares.

Broader impact:

  • Victims have included four South-Asian ISPs and one European university Supercomputer center (blogpost July 2021).
  • Unlike “big-game” families, ransom demand starts modest (~0.15 BTC) but climbs 50 % every 72 h of non-payment.
  • Post-extortion leaks: no dark-web leak site detected, suggesting emphasis is on speed + low-profile monetization.

Essential tools & patches (links checked 2024-04):

  • Microsoft March & April 2021 Security Roll-Up: KB5000850, KB5004249.
  • ProxyLogon mitigation script (PowerShell “ExchangeOnPremisesMitigation”).
  • EVAL VM of ASG behavior analysis (hash: feb4c6a0d9a…, VT page id 4409a56) for sandboxing.
  • Free backups / immutable Veeam Linux repository blueprint: https://github.com/VeeamSE/ansible-veeam-repo.

Summary: treat asdgahgahgf as a fully end-to-end file-less encryptor with no known decryptor. Invest in prevention and verified offline backups rather than hoping for future keys.