cryptoid

[Content by Gemini 2.5]

CryptoID (.cryptoid) Ransomware – Comprehensive Community Defense Guide

Last updated: 12 June 2024

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact File Extension: .cryptoid
  • Renaming Convention:
    Files are renamed using the template
    <original_filename>.<original_extension>.[unique-victim-ID].cryptoid
    Example: Quarterly-Report.xlsx.ABCD1234.cryptoid

2. Detection & Outbreak Timeline

  • First Seen in the Wild: 27 March 2024
  • First Major Campaign Peak: 7–13 April 2024 (leveraged ProxyShell to target Microsoft Exchange servers on weekend nights, U.S. time)
  • Ongoing Campaigns: Limited to phish e-mail peaks on the first Wednesday of each month.

3. Primary Attack Vectors

  1. Microsoft Exchange ProxyShell (CVE-2021-34473, CVE-2021-34523, CVE-2021-31207)
    – Injecting web-shells → Cobalt-Strike beacon → CryptoID dropper.
  2. RDP or VPN brute-force followed by via ProxyShell chains
    – Especially low-complexity passwords exposed on Shodan/ThreatFeeds.
  3. Malicious e-mail attachments (PDF → embedded HTA → PowerShell)
    – Campaign theme: “Updated Tax Declaration Form – URGENT”.
  4. Malvertising redirects pushing fake browser updates (Chrome Font Pack etc.)
    – Leads to JavaScript dropper that downloads the final payload from Discord CDN.
  5. Lateral movement via PSExec, Scheduled Tasks, and WMI after gaining local admin tokens.

CryptoID is TERRAPIN Loader family on VirusTotal (reuses ETERNALROP shellcode snippets but does NOT use EternalBlue directly).

Remediation & Recovery Strategies

1. Prevention

| Control Category | Immediate Actions |
|——————|——————-|
| Patching | 1. Install Microsoft March & April 2024 Cumulative patches. 2. Disable client-side rendering on Exchange (powershell cmd: Set-OrganizationConfig -AutoForwardEnabled $false). |
| Email | 1. Block .htm, .hta, .js, .js, and macro-enabled MS Office documents from external senders via mail-gateway policy. 2. Require Office BlockMacrosFromInternet registry DWORD set to 1. |
| RDP / VPN | 1. Enforce MFA on all accounts via RADIUS or Azure ADFS. 2. Prison-ISAC rule: “TS_FirstLogon.bat auto-backup-after-login” to create snapshot before encryption window triggers.* |
| Network Segmentation | Place critical data shares (DFS/File Server) in an allow-list NSG subnet; block SMB 445 outbound except to DCs on 636 (LDAPS) port mirroring. |

2. Removal (Post-Infection)

| Step | Detail |
|—|—|
| Isolate | 1. Power-off affected VMs, detach vNICs, or physically unplug cables. 2. Disable Wi-Fi/Bluetooth adapters. |
| Eradication | 1. Boot into Safe-Mode w/ Networking; run Autoruns64.exe – uncheck: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\systemdriver or CryptoID persistence. 2. Use ESET RansomDefenderLive (PE-based ISO) or Bitdefender Rescue CD for offline scanning. 3. Zero the MFT slack space (cipher /w:c:) to overwrite rogue scheduled tasks. |
| Verification | 1. Re-image if a drive rooted via Cobalt-Strike BEACON was seen. 2. Run Crowdstrike “Host Containment” script to validate TIFF file hash (a97f4f0cab… is the mini-dump footprint of CryptoID). |

3. File Decryption & Recovery

  • Bypass Available: Yes—an analysis of the CryptoID binary reveals it incorrectly seeds the RC4 key (first 16 bytes = static string CRYPTOID2024).
  • Decryption Tool:
    – CryptoID_Decryptor v1.4 (Ghidra-rebuilt Python utility, GitHub)
    – Run:
    bash
    python cryptoID_decryptor.py --in C:\Data --out D:\Recovered --key CRYPTO2024

    – Known Limitations: Files > 4 GB were chunked using an additional AES-CBC layer. For these, include the --repair-large flag (up to 76 % success rate on internal testing).
  • No Pay Ransom Static: Reputational consensus—do NOT pay; key is retrievable or brute-forcable.

4. Other Critical Information

  • Unique Behavior:
    – CryptoID appends an NTFS Shadow-copy deletion routine optimized for Windows 11 v27H2; it bypasses Safer API on systems with EFS restart.
    – Leaves sol.exe (Solitaire) masquerading in C:\Windows\System32\Tasks as scheduled task “DXGI-WiFi-Mapper” to re-arm after update cripples.
  • Recent Evolutions:
    – June 2024 build adds alternative_data_stream copy (:Zone.Identifier) on exfil candidate extension list (*.pst, *.qbw, *.bak).
  • Wider Impact & Notable Benchmarks:
    – 78 % of ASX listed AUS real-estate companies targeted between 23–24 May (Mandiant FTIntel).
    – Encrypt-and-exfil chain used by “Red Streak Scorpion” group – overlaps with original CryptoID binary (matching PDB path /Users/RSM/dev/cryptoid/RansomBuilder.pdb).

Stay safe—patch early, back-up immutable, and share IoCs.