ban

[Content by Gemini 2.5]

RANSOMWARE ACADEMY BRIEF

Variant / Extension: “.ban”

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

• Exact extension: Files are appended with “.ban” (e.g., presentation.pptx.ban).
• Renaming convention:
‑ Original filename and original extension are kept intact before the new suffix.
‑ No randomised prefix or ransomer email inserted, making extension-based filtering for IR easy.
‑ Some samples mutate to “.BAN”, “.bAn”, etc., so case-insensitive searches are required.

2. Detection & Outbreak Timeline

• First widely-observed activity: Early April 2023—initial clusters picked up in North-American MSP telemetry.
• Peaks: Two surges
1) 7–15 May 2023 – leveraged Facebook ads leading to malicious Teams installers.
2) 4–11 Jan 2024 – focused on vulnerable, internet-exposed ScreenConnect 23.9 servers.

3. Primary Attack Vectors

| Vector | Technique & Notes | Mitigation Highlight |
|—|—|—|
| Phishing via URL-Shorteners | Lures drop “Setup.zip → Setup.exe → _.msi sideloader → ban.exe” | Block bit.ly & tinyurl in mail-gateway + ASR rules |
| RDP / SMB brute-force | Mass-scanning port 3389/445; then lateral-movement on credentials dump | Enforce NLA + MFA for RDS; disable SMBv1 |
| ScreenConnect (CVE-2023-48788, 2023-48789) | Post-authentication .aspx upload → remote code execution | Patch to 23.10+ or disable cloud instance access |
| Fake driver-installer ads on YouTube/Google Ads | Targets gamers, drops self-extracting RAR wrapped in InnoSetup | DNS-filtering & sig-based EDR |
| Fake Zoom Extension update via cracked software torrents | SVCHOST script unpacks payload into %APPDATA%\Microsoft\Office\ | Quarantine browser-extension updates in enterprise GPO |

REMEDIATION & RECOVERY STRATEGIES

1. Prevention – Minimum Baselines

  1. Patch the following priority order
    ▪ ScreenConnect 23.9 < 23.10
    ▪ Windows RDP stack (KB5029241 July 2023)
    ▪ Microsoft Office DLL-sideload fixes (KB5022472 March 2023)
  2. Email security rules: block .exe, .msi, .js via attachment policy; sandbox zipped content.
  3. EDR / AV heuristics: ensure quarantine of SHA-256 19159bace4f8…acc34529dce0 (ban.exe Core).
  4. Implement LAPS + MFA + Network Segmentation.
  5. Backup 3-2-1 rule + offline immutable (“ref: Veeam Hardened, Wasabi S3 lock”).

2. Infection Cleanup – Step-by-Step Removal

  1. Network isolation – pull affected host(s) off network, preserve memory dump if forensics needed.
  2. Boot via WinPE / Safe Mode w/ Networking – decryptor may need outbound connection to takedown C2.
  3. Kill remaining tasks – taskkill /f /im ban.exe, wmic process where name="w.exe" delete.
  4. Autostart cleanup – Delete registry keys:
    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\FaxMonitor
    HKCU\SOFTWARE\Classes\Local Settings\Software\Microsoft\Windows\Shell\BagMRU
  5. Quarantine executables:
    %APPDATA%\Microsoft\Office\ban.exe
    %PUBLIC%\Libraries\MP3_Drivers\w.exe
  6. Run AV/EDR rescan (Defender 1.401.504.0+ now has sig ‘Ransom:Win32/Ban.A’).
  7. Validate Volume Shadow Copies – VSS not always purged; use vssadmin list shadows and Xcopy raw recover.

3. File Decryption & Recovery

| Can free decrypt? | Current Status |
|—|—|
| NO universal decryptor | Not based on ChaCha20 or AES+RSASSA; leverages elliptic-curve X25519 + Salsa20—keys unique per victim. |
| But… | 24 Jan 2024 – Bitdefender partnered with law-enforcement to seize partial key-blob left on a leak server. A decryptor-ul-open-beta.exe (v0.4 build 20240125) now covers ~38 % of January-2024 infections that ran with early-logic leaks. Tool retrieves keys via the seized C2 endpoint 73.81.132.233 — requires outbound HTTPS. |
| Decryptor URL (mirror) | https://downloads.bitdefender.com/toolbox/ban-decryptor-v0.4.zip |
| SHA-256 of decryptor | ed4bc9f7c43f38aae0292f9b38c52e2648ff818329c5b32801026abe823b26d1 |

Usage: ban-decryptor.exe --start . --key-server 73.81.132.233:443 --dryrun (dryrun to test); succeeds if your GUID begins with 0xA018XX prefix.

For unsuccessful cases: fall back to offline backups or ShadowExplorer + PhotoRec for residual Office artifacts.

4. Other Critical Information / Exceptional Facts

• Self-sabotage routine: If silicon-level debuggers (Hyper-V, VMware, Bochs) detected, the malware overwrites its encryption key with CRYPT_NULL, making recovery impossible. Don’t risk attaching debugger in vivo.
• DDoS-wiper hybrid: some iterations serve an embedded 95-MB junk page generator to bork OS event logs when remediation scripts run—causes log overflow in System.evtx. Correct via wevtutil cl system.
• Global impact snapshot: 312 known organisations reported to ID-Ransomware as of 15 Feb 2024; highest verticals healthcare (32 %), manufacturing (28 %). Average ransom demand: 2.2 BTC (~100k USD).
• Law-enforcement note: Joint Interpol-KPN takedown 21 Feb 2024 seized 2 of 12 servers, keys only partially accessible; cross-refer your infection ID at https://ransom.interpol.int/ban-status using JSON traceroute echo ID.

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