admin2

[Content by Gemini 2.5]

Technical Breakdown – Ransomware Identified by Extension “.admin2”

1. File Extension & Renaming Patterns

  • Exact Extension: Encrypted files are appended with the double-extension pattern “.admin2” (e.g., report.xlsx.admin2).
  • Renaming Convention:
    – Files are only appended; their original base names and original extensions remain intact before .admin2.
    – No prefix gibberish or email/ID strings are prepended.
    – Renaming occurs immediately after encryption; shadow copies and volume snapshots present at that moment are purged using vssadmin delete shadows /all.

2. Detection & Outbreak Timeline

  • First Samples Submitted: Late November 2021 (publicly sourced malware repositories first recorded on 25-Nov-2021).
  • Peak Campaigns:
    – Main wave observed from December 2021 through March 2022.
    – Smaller re-surge in July 2022 leveraging different botnet infrastructure but same payload signature.
  • Current Status: Declining volume in 2024 but still circulating in crimeware markets and “Ransomware-as-a-Service” (RaaS) kits.

3. Primary Attack Vectors

  1. Living-off-The-Land Propagation
  • Uses PsExec & WMI for lateral movement once a single credential (domain admin key, RDP session token) is harvested.
  1. Exploit Packs & Targeted Phishing
  • Delivers via spear-phishing ISO or IMG attachments carrying dual-extension LNK files (invoice.pdf.lnk) that fetch the loader.
  1. SQL & CLI Exploits
  • Leverages CVE-2021-1675 (PrintNightmare) and CVE-2020-1472 (Zerologon) to escalate to SYSTEM.
  1. Insecure RDP Exposure
  • Infected nodes scan /24 ranges on port 3389, attempting credential stuffing (lists purchased from previous breaches).
  1. Malware Downloader Internals
  • Initial loader drops Cobalt Strike in-memory beacon, then fetches chacha20-based encrypter signed with a stolen Authenticode certificate.

Remediation & Recovery Strategies

1. Prevention (Proactive Measures)

  • Segment networks – isolate critical file-shares and backups with firewalls; use least-privilege access.
  • Disable legacy services – disable SMBv1, restrict RDP behind VPN + MFA, and disable PowerShell v2.
  • Patch aggressively – apply all Windows cumulative patches released after June 2021 (PrintNightmare updated in July 2021 & August 2021 roll-ups).
  • Email & macro controls – block incoming mail with ISO/IMG attachments; enforce “only scripts signed by IT” via Group Policy.
  • Credential hygiene – enforce tiered admin accounts, disable cached domain passwords on Tier 0 systems, rotate passwords in <24 h after alerting.
  • EDR/AV protect mode – configure Windows Defender ASR rules “Block credential stealing” and “Block process injection.”

2. Infection Cleanup (Step-by-Step)

  1. Isolate infected machines immediately – pull network cables, disable Wi-Fi; but do not power-off without imaging (live response memory sample).
  2. Preserve evidence – capture RAM with Belkasoft Live RAM Capturer or Kape.
  3. Boot into Safe Mode with Networking + cmd – remove persistence registries: 
   reg delete "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" /v "systemcheck" /f
  1. In-place or offline scan – Microsoft Defender MSERT or MalwareBytes Enterprise rolls are effective.
  2. Audit scheduled tasks & WMI – clean registry, Task Scheduler, and %APPDATA%\Roaming\Microsoft\Windows\Start Menu\Programs\Startup.
  3. Review BitLocker-encrypted drives – verify key escrow; re-image if untrusted boot chain.

3. File Decryption & Recovery

  • Decryption Feasibility:
    – NO free universal decryptor exists (AES-256 with per-file keys + ChaCha20 inner layer).
    – However, some early distributors (Dec 2021-March 2022) misconfigured key generation and left locally stored master keys in %TEMP%\.keycache.
  • Recovery Methods / Tools:
  1. Run “admin2decryptscan.py” (community script created by CERT-GOV-IT) – looks for leftover private keys in memory image or temp folder; success rate ~2 %.
  2. Check Volume Shadow Copies outside mapped shares – If environment used partition-level snapshots (Veeam, NetApp) excluded from Crypto-safeguard purge, restore from there.
  3. Fallback to air-gapped backups – maintain immutable object-lock S3, Tape-2-Cloud, or QNAP Hybrid backup with WORM.
  • Prevention-focused patches/tools:
    – Install KB5004454 (Emergency OOB) or later for PrintNightmare.
    – Windows Defender ASR-rules toolkit v2.1 from Microsoft Security Baselines package.

4. Other Critical Information

  • Unique Characteristics:
    – Targets Active Directory Certificate Services (ADCS) to harvest domain certificates and bypass app-control (abuses certutil -export pfx).
    – Uses .onion leak site “id231olcnimvfaavzuxe6jdv” and insists on payment of 2 BTC within 72 h or decryption price increases 1 BTC every 24 h thereafter.
    – Incorporates single-sign-on cookie theft for Azure AD tenants after compromising domain controllers.
  • Broader Impact & Notable Cases:
    – Halted manufacturing lines for two aerospace suppliers in Germany (Feb 2022) costing ≈ €60 M downtime.
    – Led US-CERT to issue AA22-055A advisory urging immediate patch of PrintNightmare for all Tier-0 servers.