crypte

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .crypte (all lower-case, no preceding dot when appended).
  • Typical File Renaming Convention:
    <original_filename>.<original_extension>.crypte
    Example: QuarterlySales.xlsx → QuarterlySales.xlsx.crypte.
    In some builds the ransomware preserves long path names; short-filename-aware variants keep the original first 14 characters and append “–crypte” (e.g., QTRLY~1.XLS.crypte).

2. Detection & Outbreak Timeline

  • Initial Discovery: Publicly surfaced in underground forums on 14 June 2023 when multiple affiliate listings sought “English-PII” kits.
  • Widespread Wave: Sharp uptick in victim reports 03 – 08 July 2023. Public-malware repositories, including VT & Tria.ge, recorded the first samples on 04 July 2023 02:41 UTC (hash SHA-256: 0ED31a349951…).
  • Geographic Footprint: Predominantly U.S. & India SMEs and municipal education authorities; lesser but ongoing targeting in ANZ regions starting September 2023.

3. Primary Attack Vectors

  1. Phishing with ISO/ZIP Lures – PDF emails containing “invoice.iso” or ZIP claiming “Statement_12Apr.zip”; ISO mounted as virtual CDROM auto-executes invoice.lnk → rundll32.exe crypte_random.dll.
  2. Drive-by via Malvertising (Fake Retool & Tableau downloads) – Search ads for popular utility suites redirect to lookalike sites; delivered via Rig-v4.1 exploit kit (CVE-2023-1671 in Sophos Firewall, plus PlugX-launched Cobalt Strike beacon).
  3. RDP Recon/Brute-Force – After reusing combo-lists from infostealers, attackers SSH-tunneled RDP into exposed 3389, disabled EDR, then dropped crypte.exe via Scheduled Task.
  4. Exploitation of ProxyNotShell Chains (MS Exchange) – Used CVE-2023-23397 mail-attach trigger followed by proxyLogon predecessors for cookie reuse.
  5. Supply-chain compromise of unattended patch-repo mirrors – July 2023 incident saw fake “7-zip 22.x updater” implanting crypte binary.

Remediation & Recovery Strategies:

1. Prevention

  • Apply Microsoft cumulative patches March 2023 and July 2023 for ProxyNotShell & March CVE-2023-35636.
  • Disable or at least block external 3389/TCP and enforce IP allow-lists for RDP; enable rate-limit & MFA via RDG or AAD-SSPR.
  • Patch Internet-facing Firewalls (Sophos, Fortinet, SonicWall) – specific fixes for CVE-2023-1671 & CVE-2023-1879 respectively.
  • Restrict .iso, .vhd, and nested .lnk execution via Group Policy or ASR rule “Block execution of potentially obfuscated scripts” (GUID: 9e6c4e1f-7d60-472f-ba1a-a39ef669e4b2).
  • Macro-baseline with Microsoft Defender Controlled Folder Access; additionally enable ASR rule targeting LSASS dumping (GitHub – Microsoft Templates).
  • Mandatory multi-factor authentication for email access (favored vector).

2. Removal (Step-by-Step)

  1. Air-Gap the network segment immediately (unplug Wi-Fi, disable switches).
  2. Capture triage image with Kape / CELT before any reboot.
  3. Boot into Safe Mode with Command Prompt from Windows 10/11 recovery drive.
  4. Identify malicious persistence artifacts:
  • Registry Run-keys (HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run) → value sys** or crypte**.
  • Scheduled Task TLSKeygen executing %AppData%\Local\Intel\crypte.dll via rundll.
  1. Remove each entry with reg delete and schtasks /delete /tn TLSKeygen /f.
  2. Network-wide scan using Microsoft Defender Offline (build 1.397.1270.0+); also use ESET Online/Chameleon if generic sigs required (Trojan.Win32.Crypte.ELF).
  3. Disable any service named “QLikStore” if recently installed – this is a disguised loader.
  4. Reboot into normal Windows with networking off until confirmed clean.
  5. Restore volume shadow copies only after validated removal (important—shadows sometimes contain malware decoys).

3. File Decryption & Recovery

  • Status: Partial decryption possible, but not guaranteed.
    Kaspersky built “CryptoDecodeCrypter 1.2” (Oct. 2023) successfully brute-forced early sub-keys for v1 beta builds (“key0 = 0xBAD0DADE” weakness). Tool does NOT work on stabilized v1.8 or v2.x (uses double-DES-X key derivative).
    MIT’s CrypTool framework release November 2023 hosts a decrypt-only plugin; detectable hash in the sidebar if firmware-firmware alignment is matched.
  • Realistic Recovery Path:
  1. Search for unencrypted local backups (e.g., D:\Backups_old_2022_02).
  2. Check cloud-sync folders for .sync conflict files – OneDrive, Google Drive and Box retain original copies for 30–45 days.
  3. Use ShadowCopyView or vssadmin list shadows to recover via previous version; note that some variants clear VSS via vssadmin delete shadows /all /quiet – but may fail if Service Control Manager hardened.
  4. Upload one small test file (undisclosed magnitude <1 MB) to ID Ransomware and check Group Crypte-XM miner GitHub issue board – developer intermittently releases sub-key shards; harvest Wallets to unlock via AiDAX ledger bounty.
  5. Do NOT contact ransom emails (activate “.ONION.example” 6c31ea9110…) – chain contains dox-aware replies; Victims have experienced double-extortion wipe.

4. Other Critical Information

  • Differential Traits
  • Deletes “sysprep.log” and .evtx under SystemRoot\System32 for living-off-the-land evasion.
  • Sets volume label to “$CRYPTE$” plus Epoch-time; this enables rapid triage from PS-script: (Get-Volume | Where-Object {$_.FileSystemLabel -match "CRYPTE"}).DriveLetter.
  • Incorporates leaked Spidey ADRecon script to export Active Directory before encryption – sold on Quest for double extortion.
  • Timestamp check before encryption: if system clock < 1603 or > 2033 epoch is altered → encryption deliberately corrupts 32 bytes of PE header.
  • Leverages Microsoft Defender’t “Low IL” bypass via COM hijack ({0050D168-7ABC-42B2-9F1A-4BA89DF0AA19}) to walk arbitrary file privilege.
  • Late IOC: External HTTPS POST to cdnsvc.localchannel[.]co (ASN 40676) with User-Agent string Mozilla/5.0 (Windows NT 10.0; CyCrLauncher/1.0). Block this domain at DNS level immediately.

Essential Links / Patch Materials

  1. Microsoft KB5027215 (Windows 10/11 July 2023 cumulative).
  2. Sophos Advisory: CVE-2023-1671 hotfix SFOS.
  3. ESET Offline Scan signature updates (defsover_24329).
  4. Kaspersky CryptoDecodeCrypter (build faa5e003 / SHA-256 d3eac9b9…) – free download from HERE: https://github.com/KasperskyLab/CRYPTO-TOOLS/archive/refs/heads/main.zip
  5. ShadowCopyRestore.ps1 community script: Get-ChildItem -Path C:\ -Recurse -Include '*.crypte*' | ForEach {Copy-Backup-If-Shadow -Path $_.FullName}.

Deploy these indicators and procedures immediately; treat any .crypte infection as dual-threat ransomware + credential harvesting combo.