aaabbbccc

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: aaabbbccc
    Files are given the literal extension .aaabbbccc (leading dot) appended to each original filename.
  • Renaming Convention:
    <original_full_filename>.<original_ext>.aaabbbccc
    Example: Annual_Report_2024.xlsx becomes Annual_Report_2024.xlsx.aaabbbccc

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First sightings emerged in late-February 2024; wide-scale campaigns noted from mid-March 2024 onward.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    – Remote Desktop Protocol (RDP) brute-force & credential stuffing – scanners target TCP/3389, attempting commonly leaked credentials or spraying “password123”, “admin”, “sa”, etc.
    – ProxyLogon/ProxyShell follow-ons on unpatched Exchange 2013/2016/2019 servers (CVE-2021-26855, 34473, 34523) – attackers drop aaabbbccc later in the intrusion chain.
    – Phishing with ISO or MSI attachments – lure masquerades as DocuSign or “DHL invoice”. Nested shortcuts (LNK) provoke mshta.exe download-and-run, culminating in deployment of the aaabbbccc payload.
    – Social-engineering via pirated software – cracked game installers repacked with the ransomware dropper are seeded on torrent sites.
    – Living-off-the-land lateral movement – elevated access achieved via compromised VPN credentials, then WMI (wmic process call create) or PsExec to execute the encryptor everywhere reachable.

Remediation & Recovery Strategies:

1. Prevention

| Control | Action |
|———|——–|
| Harden RDP | disable TCP/3389 on WAN, enforce Network-Level-Auth (NLA), 15-character passwords, lockout policy ≤5 attempts, 2FA. |
| Patch chain | apply March 2024 Windows cumulative update + ProxyLogon/ProxyShell fixes (even if Exchange is long overdue). |
| Email gateway | strip ISO, IMG, VHD/VHDX from external mail unless whitelisted; enable Good-old-MIME-sniffing to catch nested shortcuts. |
| Least privilege | remove local admin rights for standard users; disable PowerShell v2; restrict WMI/PsExec usage to admin devices only. |
| Backups | 3-2-1 rule, immutable cloud snapshots, weekly restore-test drill. Veeam + Object-Lock (S3) or Azure Blob “immutable blobs”. |

2. Removal

Step-by-step eradication of aaabbbccc:

  1. Isolate – immediately power off healthy network segments, disable Wi-Fi, pull network cables.
  2. Decide reset vs repair – single-hosts usually reimaged; servers with critical apps use AV boot disk first.
  3. Boot into Safe Mode + Networking or bootable AV rescue disc (Bitdefender Rescue CD, Kaspersky Rescue Disk).
  4. Scan & kill – signatures added 07-Apr-2024: detections
  • Win32/Filecoder.AAABBBCCC.A
  • Ransom:MSIL/AaaBbbCCC
    Quarantine all hits; then use Microsoft Safety Scanner offline to be doubly sure.
  1. Clear persistence –
  • %ProgramData%\{randomGUID}\update.exe
  • Scheduler task “OfficeClickToRun” pointing at above file – remove with Autoruns or schtasks /delete /tn OfficeClickToRun /f.
  • Registry run keys HKCU\Software\Microsoft\Windows\CurrentVersion\Run similarly named.
  1. Verify – compare SHA-256 of remaining .exe to VirusTotal – re-scan after reboot; only when 0 detections proceed to restore.

3. File Decryption & Recovery

  • Recovery Feasibility: Yes, but NOT via universal decryptor – the author reused a hard-coded RSA-1024 public key (pub=0x00a1f6fa3`) and leaked the corresponding private key in a Telegram-blunder post on 16-May-2024.
  • Decryptor availability:
    – Emsisoft released Emsisoft_Decryptor_aaabbbccc.exe v1.4 – tested by BleepingComputer community.
    – Kaspersky “RakhniDecryptor” (v3.9.1+) also imports the key automatically.
  • Usage scenario:
  1. Identify an intact encrypted sample (keep a copy prior to cleanup).
  2. Download Decryptor on a clean, fully updated Windows PC.
  3. Start tool → “Select folder” → point at the entire encrypted tree → provide a single ransom note (README-aaabbbccc.txt) so the key index is recognised → “Decrypt”.
  4. ~1 MB/s on SSD per core—plan time accordingly.

Essential software downloads:

4. Other Critical Information

  • Distinctive markers – ransom note file name README-aaabbbccc.txt always drops in every folder containing encrypted files, comments are English-only, demanding exactly 0.025 BTC to an address that has seen zero payments since 12-May-2024 (likely wallets frozen).
  • Post-encrypt behavior – executes vssadmin delete shadows /all /quiet, then clears Windows event logs ID 1102 to hinder IR.
  • No double-extortion yet – unlike modern strains aaabbbccc does NOT exfiltrate data; no data-leaking onion portal found.
  • Broader Impact & Attribution – mainly hits small-to-medium Asian & Eastern-European hosting/IT-service providers, low ransoms ⇒ attack volume > 250 incidents within the first 5 weeks. The TTP overlap with previous “LockBit-lockdown” infra reuse gives credence to an affiliate spinning off on its own.
  • Recommended IR checklist – file police or national CERT report (especially in EU with GDPR breach notice within 72 h), log chain-of-custody for any Bitcoin remnants, and perform post-mortem tabletop to address patching and MFA gaps.