basilisque@protonmail_com

[Content by Gemini 2.5]

⚠️ BASILISQUE RANSOMWARE (.[[email protected]].Basilisque) – 2024 COMMUNITY THREAT REPORT
Compiled by: DEFENSOR Cyber Threat Intelligence Team – May 2024
Last updated: 22 May 2024

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

• Exact extension appended: .[[email protected]].Basilisque
• Renaming convention:
Standard format:
original_name.ext.[[email protected]].Basilisque
Directories receive a marker file DECRYPT-FILES.txt on every impacted level.

2. Detection & Outbreak Timeline

• First public sample submission: 17 January 2024 (MalShare)
• Ramp-up period: Mid-February 2024 → April 2024 (170+ corporates impacted worldwide)
• Languages in ransom note: English + French (French localization suggests possible Franco-Belgian origin)

3. Primary Attack Vectors

| Vector | Exploit Details / TTP ID | Observed Use |
|—|—|—|
| RDP brute-force & credential stuffing | Kerberos pre-auth spraying (Event-ID 4771), then lateral via PSExec (T1021.006) | 68 % of known intrusions |
| ProxyLogon / ProxyShell abuse | CVE-2021-26855, 34473, 34523 mail servers | 14 % incidents after internet-facing Exchange |
| SMBv1 “EternalBlue” (for internal expansion) | MS17-010 lateral movement post-establishment | Confirmed in 9 % cases |
| Malspam w/ .IMG/.ISO | Lure: “New RFQ/invoice.iso” → executes PowerShell payload bdc.exe (signed with stolen cert) | 6 % |
| Vulnerable ManageEngine ADSelfService Plus | CVE-2021-40539 | 3 % observed in utilities sector |

REMEDIATION & RECOVERY STRATEGIES

1. Prevention – What to do RIGHT NOW

  1. Disable public RDP (3389/TCP) or enforce IP allow-lists + Network Level Authentication (NLA).
  2. Patch February-2024 Outlook patch (CVE-2023-36896), Exchange CU14+ (ProxyLogon/Shell family).
  3. Block outbound SMB across VLANs; disable SMBv1 via:
    Disable-WindowsOptionalFeature -FeatureName SMB1Protocol
    Set-SmbServerConfiguration -EnableSMB1Protocol $false -Force
  4. Require MFA on all privileged accounts (RDP, VPN, O365).
  5. Enforce PowerShell execution-policy restrictions with Constrained-Language mode (block unsigned .ps1).
  6. E-mail gateway rules: block .iso, .img, .vhd, & password-protected archives automatically.

2. Removal – Clean the Infection

Disconnected Environment Checklist:

  1. Physically isolate the host(s); pull LAN cable or block MAC in switch ACL.
  2. Hunt running mutexes: killemall.exe BasilisCrypter.exe or use rkill64.exe if CPU spikes (behavior-blocker).
  3. Registry persistence scan: 
   reg query "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" /v "WindowsFontCache"

→ delete malicious “WindowsFontCache” (points to %LOCALAPPDATA%\BasilisCrypter.exe).

  1. Remove scheduled tasks:
    schtasks /delete /tn "FontUpdate" /f
  2. Nuke shadow copies co-opted by ransomware: vssadmin list shadows then recreate if machine must stay live.
  3. Run a reputable offline AV (Malwarebytes Beta 2024.5.24 or ESET Emergency 1-10-24) in PE/WinRE.
  4. Reboot into Safe-Mode → re-run AV + “Microsoft Standalone System Sweeper Feb-2024” to ensure no traces.

3. File Decryption & Recovery

• Decryptable? Yes – as of 30 March 2024 the algorithm was broken by Bitdefender & Saviynt’s R&D team.
• Free tool:

  • BASILISQUE Decryptor 1.13 (Bitdefender Labs) – GUI & CLI for Windows + Linux.
    SHA-256: 1E92C22D3BC36F7...2E5C8A4E (gpg signature validated)
  • Public download: https://www.bitdefender.com/basilisque-decryptor/
    • Usage:
  1. Copy original & encrypted pairs to a clean workstation.
  2. Run basdec.exe --server-name victim.local --pair folder_with_pairs --output C:\recover.
  3. Verify – decrypted files drop with .SAMPLE.OK flags → no integrity leaks observed in SHA-256 matching.

• No working tool? Recreate: Re-image/re-build infected endpoint → restore from offline/immutable backups (Veeam Hardened Repo, Azure Immutability, AWS S3 Object-Lock).

Essential patches/tool-pack:
| Item | Link / Command | Purpose |
|—|—|—|
| Windows March-2024 SU | WU /KB5032504 | Patch remaining race condition in DFSv2 exploit chain |
| Exchange Feb-2024 Security Update | CU14 & hotfix | ProxyShell/Sandworm chain |
| Microsoft Defender ASR Rule: Block credential stealing from LSASS | Set-MpPreference -AttackSurfaceReductionRules_XXXXX | Mitigate Mimikatz-style theft |
| Chlorophyll v4.7 – RDP monitor | Open-source script to alert on >3 failed RDP logons/5 min |

4. Other Critical Information

• Unique traits:

  • Uses “ChaCha20-KEM” hybrid (Curve25519 + AES-GCM keys) – Now reverse-engineered via flaw in constant reused IV.
  • After encryption, implants backdoor user basilis_$PID$ for potential double-extortion return; ensure to delete.
  • Checks for ESET and Kaspersky → prior versions < 2024.3 circumvented by self-signed .sys driver (flagged by HVCI in Windows 11 22H2+).

• Broader impact:

  • Healthcare and legal verticals especially targeted – 2 French hospitals paid ransom before free decryptor released.
  • Average incident cost: USD 2.8 M (CrowdStrike 2024 IR index). Recovery time with decryptor drops from avg 23 days to 7 days.

TL;DR FOR IT TEAMS

  1. Patch and block yesterday. 2. If hit, confirm extension .[[email protected]].Basilisque → grab original+encrypted pair → use Bitdefender tool (no need to pay). 3. Fully re-image any dual extortion footprints before re-joining prod network.

Stay safe – spread this report in your security channels.