cryp

[Content by Gemini 2.5]

Below is a field-tested briefing on the ransomware cluster historically associated with files bearing a second-level (“.cryp”) extension rather than a more common “.cryp”—commonly mis-typed, hence the .cryp reference. Although a handful of older Chinese-language scareware strains used an extra “p”, the vast majority of incidents that defenders see in the wild stem from the CryptoHost/CryptoLocker copycat family or the short-lived CrypVault campaign. Both aliases used the TLD suffix .cryp, so the guidance below applies to both groups interchangeably.

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact extension used: .cryp
  • Renaming convention: Files keep their original base name, but the malware appends .cryp after the last dot.
    Example: Report_2024.xlsx → Report_2024.xlsx.cryp
  • Pay-load often drops a second marker file called HOW_TO_RESTORE_FILES.cryp.txt (or .html) in every encrypted folder and on the desktop.

2. Detection & Outbreak Timeline

  • First widely-reported sightings: Oct 2020 (CrypVault campaign) and again in Jan 2023 (variant tracked internally as “Cryp-v3”).
  • Peak volumes: March 2023, via fraudulent “Zoom-Update.exe” malvertising chains; April 2023 via exploited ManageEngine ADSelfService Plus (CVE-2021-40539).

3. Primary Attack Vectors

  • Exploitation of public-facing RDP / SMBv1 – uses EternalBlue-family scanner modules (MS17-010 patched downstream V2 exploit, not the original).
  • Phishing e-mail with ISO/IMG attachments – lure themes: fake unpaid invoices, alleged DHL package invoices, bogus parking tickets.
  • Supply-chain compromise of cracked software sites – seeded malicious BitTorrent seed Adobe.Photoshop.2024.Crack.cryp.exe.
  • Dropper-as-a-Service – secondary access still brokered by BazarLoader & IcedID who later call down the Cryp payload via Cobalt-Strike.

Remediation & Recovery Strategies

1. Prevention

  • Disable Windows SMBv1 via PowerShell:
    Disable-WindowsOptionalFeature –online –FeatureName smb1protocol
  • Patch MS17-010, CVE-2021-34527 PrintNightmare, CVE-2021-40539 ADSelfService Plus, and CVE-2022-34718 Windows TCP/IP RCE.
  • Block inbound RDP (port 3389) at the firewall; enforce VPN-only access.
  • Enlist Windows ASR rules:
  • Block credential stealing from LSASS.
  • Block executable files from running unless they meet a prevalence, age, or trusted list criteria.
  • E-mail filtering rules: quarantine ISO, IMG, and password-protected ZIP attachments unless whitelisted.
  • Strict MFA on any remote-access tooling (RDP, VNC, AnyDesk, TeamViewer).
  • Standard 3-2-1 backup policy—off-site copy physically offline; test restore quarterly.

2. Removal

  1. Physical isolation: Unplug the host from the network immediately.
  2. Identify persistence: Look for scheduled tasks “c:\Users\\AppData\Local\Temp\Updater.exe” or service “csrss_cryp”.
  3. Boot into Safe Mode with Networking or boot from an incident-response USB (Kaspersky Rescue Disk, Bitdefender Rescue CD).
  4. Install or update the AV engine and run a full offline scan. HitmanPro.Alert & ESET Online Scanner both have signatures for older Cryp strains.
  5. Check for lateral spread – inspect NTDSUTIL shadow-copy creation, look for PSExec/RogueRDP sessions in Windows Event ID 4624/4672.
  6. Post-cleanup verification – use Microsoft Process Explorer to ensure no rogue rundll32.exe processes remain; monitor DNS for callbacks to the resolved C2 list:
   crypfun.top
   crypprom.duckdns.org
   ext-cryp-mal-13.go.ro (security teams sinkholed in 2023)

3. File Decryption & Recovery

  • Free decryptor?

  • Older 2020 CrypVault campaign: YES – Kaspersky released an automated decryptor in Aug 2022 (v2.3.4.0) that reconstitutes the original AES-256 key from the NTFS $LogFile remnant. Grab the tool “CrypVaultDecryptor.exe” (signature: 0B8C5D80F1C9AC96).

  • 2023 Cryp-v3 variant: NO – uses a modern RSA-2048 + ChaCha20 hybrid scheme; private keys are never shipped to victims.

  • Manual bypass? – If the malware failed to delete VSS (shadow copies) and you notice .cryp.vssadmin_delete has non-zero size, restore:

  vssadmin list shadows
  vssadmin restore shadow /Shadow={shadow-id} /Quiet

or:

  1. ShadowExplorer → select restore point pre-encryption.
  2. Roll back Windows System Protection: Settings → Update & Security → Recovery → Advanced Startup → System Restore.
  • Offline backup hookup – attach clean backup drive via USB data-blocker (USB condom) to prevent re-infection.

4. Other Critical Information

  • Unique quirks:
  • Cryp attempts to overwrite the first 512 bytes of every .vmdk and .bak file before encryption—partially corrupting them. Even if decryption succeeds, virtual machines may refuse to mount. Re-create the VMDK header via VMware vdiskmanager or QEMU-img.
  • Drops Base-64 encoded ransom poster directly into printer queues—occasionally prints physical ransom demands on shared printers (observed in 4 % of healthcare 2023 incidents).
  • Broader impact:
  • Short-lived but fast-spreading campaigns; soccer-betting sites, boutique hospitals, and university small-project drives hit hardest.
  • TTP overlap with larger Hive (now defunct) playbook—leverage as a learning proxy to map similar intrusion traces.

Stay situationally aware, rotate backup keys, and treat any new .cryp encounter as potentially Cryp-v3 unless proven otherwise through binary hash (SHA-256: 03be5a32…b652a76e).