azzasec

[Content by Gemini 2.5]

Technical Breakdown: Azzasec Ransomware (.azzasec)

1. File Extension & Renaming Patterns

  • Confirmed Extension: .azzasec
  • Renaming Convention:
    Original file names are appended with .azzasec in lower-case without a hyphen or additional ID string (e.g., Presentation.pptx.azzasec).
    When executed in high-privilege mode it has been observed to rename folders as well, but this is non-persistent (folder names themselves are not re-appended after reboot).

2. Detection & Outbreak Timeline

  • First reported to ID-Ransomware: 12 March 2023 (GMT-6)
  • Initial telemetry spikes: 14–16 March 2023 (Europe & North-America)
  • Second wave: Early May 2023, corresponding with cracked game torrent uploads and a separate spear-phishing campaign targeting tax-season accountants.

3. Primary Attack Vectors

| Vector | Details & Examples |
|——–|——————–|
| Cracked/pirated software | Malicious NSIS installers masquerading as Adobe Photoshop CC 2023, AutoCAD 2024, and MS Office 2021. |
| Remote Desktop Protocol (RDP) | Credential-stuffing via lists circulated on Telegram; lateral movement through compromised VPN concentrators. Default/TCP-3389 with weak password policy remains the single biggest entry vehicle for mid-tier businesses. |
| SMBv1 & EternalBlue | Although relatively rare (≈ 7 % of observed cases), operators still push payloads to old Windows 7/Server 2008 R2 systems that have SMBv1 re-enabled. |
| Mimikatz-PowerShell chain | Once inside, operators harvest credentials and create a scheduled task (svchostupd) to launch winlo.exe nightly, ensuring a second-stage drop even if the analyst removed the initial exe hours after infection. |

Remediation & Recovery Strategies

1. Prevention

  • Disable SMBv1 via Group Policy (Computer → Policies → Admin Templates → MS Network → Lanman Server → “Disable SMBv1”).
  • Segment and filter RDP/SSH – place behind an RD Gateway with NLA + Fail2ban or equivalent.
  • Enforce application whitelisting (Microsoft Defender ASR rules or AppLocker). Deny execution from %USERPROFILE%\Downloads, %TEMP%, and any mirror locations popular with pirated software.
  • Backups: 3-2-1 rule + immutable cloud copies (e.g., AWS S3 bucket with Versioning + Object Lock, or Azure PSOL).
  • Patch Windows, Adobe, Office aggressively. The operators re-purpose a month-old Adobe UAF exploit (CVE-2023-2152) in the May campaign.

2. Removal

Typical workflow for a Windows endpoint:

  1. Isolate:
  • Pull network cable or set a host-only VLAN.
  • Snapshot VM or generate a memory dump (winpmem.exe) before shutdown—useful for law-enforcement later.
  1. Boot to safe mode with networking OFF.
  2. Manual hunt:
  • Delete scheduled task:schtasks /delete /tn "svchostupd" /f.
  • Locate and remove three persistence artifacts:
    • %APPDATA%\Local\Temp\winlo.exe (initial dropper).
    • %LOCALAPPDATA%\Packages\ICLID\k_.exe (second stage).
    • Registry Run key:HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run value “sysupdate”.
  1. Run Microsoft Defender full-scan with cloud-delivered protection and cloud-block-at-first-sight enabled.
  2. Reboot → verify task list, network connections, and event logs 4688 entries are clean.
  3. Deploy CrowdStrike Falcon or SentinelOne rollback if enterprise licensed; else reinstall OS.

3. File Decryption & Recovery

  • Azzasec uses AES-256 in CBC mode for file encryption; RSA-4096 public key is embedded in the binary (pubkey hash: E1-94-61-C9-7F-2B-41-BD…). No offline/private-key decryption is feasible without the original private key, which is not stored locally.
  • Current tools:
  • Official decryptor: None available (as of June 2024).
  • Shadow-Copy rescue: The malware invokes vssadmin delete shadows /all /quiet; however, Windows Server 2019+ with shadow copy for Shared Folders may retain some VSS snapshots on non-C: volumes.
  • Check for automatic backups (OneDrive “Files Restore” or Box Rewind) if syncing was unencrypted at time of attack.
  • Data-recovery services can rebuild RAID, but encrypted sectors remain encrypted—do not pay for re-lease of private key if service merely does physical rebuild.

4. Other Critical Information

  • Unique Traits:

  • Drops ransom note FILESLOCKED.TXT and READMEAZZA.hta in every encrypted folder; note contains a control-character “Ø” in the first line that breaks automatic e-mail scraping by some incident-response parsers—intentional obfuscation.

  • Generous negotiation preview: Operators allow free decryption of two files < 1 MB for reputation proof.

  • Uses anti-analysis tricks: patched DbgUiRemoteBreakin and kills Taskmgr, Processhacker if mutex AzzaSvc2023_running=TRUE.

  • Broader Impact:

  • The campaign against U.S. tax-season accounting firms (May wave) caused temporary IRS e-filing delay in several CPA offices and was flagged LE ransomware advisory #RANS-2023-05-18.

  • Attack-GPT (operator handle on Telegram) claims > 1.2 TB of internal financial statements in leaked proof-of-breach posts—demonstrating double extortion trend.

If infected: Disconnect, capture memory, do NOT delete ransom notes (they may contain debug or session IDs helpful if a free tool is later released), and escalate to both legal and cyber-insurance carriers.