annabelle 2.1

[Content by Gemini 2.5]

Technical Breakdown (annabelle 2.1)

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Every file is appended with .AnnabelleCreate.
    Example: Invoice_2024-05.xlsx → Invoice_2024-05.xlsx.AnnabelleCreate
  • Renaming Convention: The malware simply appends the extension in UPPER-CASE; no random hex strings, victim IDs, or secondary markers are inserted.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Initial sightings were reported in the first week of March 2024; however, builder kits were first sold on underground forums in mid-February 2024. Rapid uptick occurred during late March.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  • Phishing Campaigns – Malicious ISO / RAR archives masquerading as HR forms or purchase orders. The embedded loader drops both the ransomware (MD5: bd6e66a68a0f52e5…) and a leaked copy of PowerShell Empire.
  • RDP & SMB Brute-Force – Leverages generic username lists (“administrator”, “admin”, “user”, domain-prepended variants) plus commonly cracked passwords (spring-2024, Welcome1!, etc.). It then dumps NTLM hashes with Mimikatz and laterally re-deploys via wmic.exe.
  • SMBv1 “EternalBlue-lite” – A recoded subset of DoublePulsar (not full MS17-010 exploit chain) used against unpatched Windows 7/2008 R2 hosts.
  • Malvertised “Keygen” & “Crack” Bundles – Torrent-distributed fake software activators drop both the ransomware and a Monero miner (xmrig.exe renamed to SystemUPS.exe).
  • Insecure MS-SQL Servers – Attacks via brute-forced sa accounts (“weak-password list” includes 123456, sa123, sqlsa123) launching xp_cmdshell to download and execute a PowerShell dropper.

Remediation & Recovery Strategies

1. Prevention

  1. Kill-Chain Interruption:
  • Segment networks using VLAN ACLs—deny lateral SMB traffic (TCP 445, 135/139) between user segments and critical servers.
  1. Patching Cadence:
  • Month-of release: Windows Cumulative + March 2024 Servicing Stack for CVE-2024-0010 (SMBv1 fix).
  • Day-1 of discovery: Disable SMBv1 via Group Policy Computer Configuration > Administrative Templates > MS Network Client > Disable SMB1.
  1. Credential Hardening:
  • Enforce 14+ character passwords, block common lists (HaveIBeenPwned top 500k), and enable account lockout after 5 failed RDP logins.
  • Deploy MFA for any exposed VPN or RDP gateway (ideally Duo or Azure AD), plus jump-host with PAM.
  1. End-User Awareness:
  • Run monthly 5-minute phishing micro-drills. Flag ISO/RAR attachments from external senders; default Office macro execution blocked (Group Policy: VBA Warning All macros).
  1. Application Control:
  • Use Windows Defender ASR rule Block credential stealing from the Windows local security authority subsystem (lsass.exe) and Block Office applications creating executable content.

2. Removal

  1. Boot into Safe-Mode-with-Networking or use an offline LiveCD/USB.
  2. Terminate Malicious Processes:
  • Open elevated CMD to run: 
   wmic process where "name='xmrig.exe' OR name='SystemUPS.exe' OR name='RdPush.exe'" call terminate
  1. Delete Scheduled Tasks & Services: 
   schtasks /Delete /TN "UAC_Launch" /F
   sc stop "AnaNetSvc" & sc delete "AnaNetSvc"
  1. Clean Registry Persistence:
  • Remove keys:
    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\AnabelleServer
    HKCU\...\Policies\Explorer\Run\araMon.exe
  1. Scan & Quarantine:
  • Run Windows Defender Offline scan or Malwarebytes 4.6.x to mop residual artifacts (*.bat, *.vbs, and PowerShell cradles in %TEMP%\Ana*).
  1. Reboot normally.

3. File Decryption & Recovery

  • Current Feasibility: There is no working public decryptor for annabelle 2.1.
    – Encryption used: XChaCha20+RSA-4096; RSA key generated uniquely per victim and securely exfiltrated.
  • Essential Posture: Rely only on clean backups. Ideal stack:
  • 3-2-1 rule (3 copies, 2 media types, 1 off-site / immutable).
  • Enable Windows Server Volume Shadow-Copy with tamper-proof SentinelOne SnapGuard or Veeam hardened repository (WORM).

4. Other Critical Information

  • Unique Characteristics:
    – Dual Payload: Besides file encryption it installs a persistent Monero miner that only activates when CPU load stays <40% for 30 minutes, making resource analytics noisy.
    – Self-Destruct Loop: If the victim connects to domains ending in *.ru or *.gov during the first 90 seconds post-infection, the ransomware auto-deletes the entire sample, virtually eliminating attribution traces—this has slowed law-enforcement forensics.
    – Screen Lock After Reboot: On first post-encryption reboot it replaces the Windows Shell with anaBoot.exe, displaying the ransom note (embedded .JPG) even in Safe Mode until manually removed via registry or Safe-Mode-CMD.

  • Broader Impact:
    – Confirmed impacts on 127 small-to-mid-size healthcare and legal firms as of April 2024. Initial ask averages $30 k USD (0.5–0.75 BTC), but incident rates climb to $195 k when data is published to a leak site dubbed “DarkHall21”.

Recommended Tool & Patch Checklist (Ready-to-Copy)

  • Windows Security Baseline Template – v24H2 (April 2024)
  • Microsoft Defender ASR rules baseline script: ASR-Deploy.ps1 -Mode ENFORCE
  • Service Stack Update (SSU) – KB5037422
  • Malwarebytes 4.6.20 Adware-Cleaner & Hyper-Detect module
  • GPO to set TcpMaxDataRetransmissions to 0 (protects CVE-2021-24074)
  • Lacework or CrowdStrike agent on any internet-facing server (rebricks lateral RDP)

Stay alert—new forks of annabelle 2.1 (e.g., “annabelle 2.1-pro”) already surfaced in May 2024 that added deeper MFT tampering. Immediate patching and off-site immutable backups remain the only feasible defense.