Dharma Ransomware Community Resource Guide

(Last updated: 2024-05-20)

Technical Breakdown

1. File Extension & Renaming Patterns

Confirmation of File Extension: .[original-filename]-[{ UNIQUE-ID }].[attacker-supplied e-mail(s)].dharma
Example: Document.docx.id-9EC4A301.[[email protected]].dharma
Renaming Convention:
– Keeps the original file name in the beginning.
– Appends a victim UID (usually 8–10 hex characters).
– Lists one or more attacker e-mail addresses.
– Finishes with the literal .dharma suffix.
– Long paths or names are NOT truncated, so file lengths can exceed Windows’ 260-character legacy path limit.

2. Detection & Outbreak Timeline

First public sighting: November 2016 (initially misidentified as “CrySiS”); active branch codes generally tracked as “Dharma-CrySIS-COBRA” family.
Peak waves:
– Q2 2018–2019: Massive drive-by SMB/NetBIOS campaigns tied to exposed RDP.
– 2020: Up-tick in COVID/health-care targeting.
– 2022–2024: Solid affiliate model with underground RaaS (i.e., the “Babuk spin-off factions”).
Current status: Still circulating every week via new affiliate spam, binary forks, cracked installer bundles (KMS, pirated games), and double-extortion sites (DLS).

3. Primary Attack Vectors

Exposed RDP (TCP 3389 / 33891)
– Credential-stuffing, password-spray, with tools like NLBrute or Router Scan.
Vulnerabilities Leading to RDP
– BlueKeep (CVE-2019-0708), the now-ancient “EternalBlue” pivot once an initial foothold is gained.
Malicious attachments & exploit docs (PE) bundles
– Fake COVID grants, FedEx/UPS invoices, or cracked software silently dropping the loader.
Sub-domain / Phishing Redirects
– Coffin-redirect traffic via compromised WordPress sites.
Double-Extortion
– Steals data first with MEGASync upload or ScreenConnect exfil scripts, then deploys Dharma.

Remediation & Recovery Strategies

1. Prevention

Patch Remote Access aggressively
– Plug Remote Desktop Services / RDP behind a hardened VPN/Gateway and enforce Bastion Host logging.
Disable Legacy SMBv1 entirely (Disable-WindowsOptionalFeature -Online -FeatureName "SMB1Protocol").
Credential rules:
– Enforce 15+ character passwords, NTLM-rate limiting, lockouts (5/5/30), and MFA** on every remote access protocol.
Application allow-listing via WDAC / AppLocker or Microsoft Defender ASR to prevent unsigned payloads.
Network segmentation (“Zero-trust”): isolate servers from workstations, limit SMB/RPC/IPC shares to absolutely essential ports.
Back-up hygiene: 3-2-1 back-ups with offline or immutable storage (e.g., WORM for S3, Azure immutable blobs, vSphere hardened backup jobs).

2. Removal – Clean-up Checklist

Quarantine network segment once ransomware behaviour detected.
Boot infected devices into Safe Mode with Networking.
Disable spawned services or scheduled tasks (usually created in %ALLUSERSPROFILE%\Microsoft\Windows\Start Menu\Programs\Startup\Info.exe).
Run a reputable AV/EDR with offline scanner (Malwarebytes 4.x, Sophos HitmanPro.Alert, Microsoft Defender Offline).
Delete registry keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run or HKLM…\RunOnceEx referencing the random executable names (umsdcxxx.exe, srvhost.exe, etc.).
Re-image / golden-image restore is generally the fastest way to ensure complete cleanup (Dharma occasionally leaves “sleepers” like scheduled PSExec or ScreenConnect backdoors).
Scan for Cobalt Strike beacons (look for named pipes that start with \\.\pipe\ followed by random hex) before bringing the host back online.

3. File Decryption & Recovery

Is decryption possible?
– YES, ONLY for the legacy Dharma-February-2017 keys: the master RSA private was leaked by ESET and Avast.
Official decryptors (may decrypt your files if they match the February 2017 keyset):
– ESET CrySiS Decryptor (free): https://www.eset.com/us/support/tools/
– Avast Decrypter for CrySiS (GUI-based): https://www.avast.com/ransomware-decryption-tools

Limitation: These tools do NOT work on any of the newer branches (2018–2024). Confirm your ransom note is identical to the February 2017 template; if not, NONE of the above utilities will work.

No-viable-decryptor action plan:
– Restore from immutable backups (Veeam SureBackup, Commvault air-gapped, Azure Blob immutability, Cloudian object lock, etc.).
– Contact professional IR teams; some affiliates have quietly accepted to give back the key for cooperative small/medium organizations instead of facing law-enforcement heat.
Essential patch/software lists:
– KB4523205, KB4499164 & later (August 2019 patch roll-ups) – mitigate BlueKeep/EternalBlue.
– .dharma v10 now also fingerprints on Citrix ADC (CVE-2019-19781) – apply latest firmware.
– Update Java & Adobe Reader (PDFs used with double-click exploits).
– Ensure Windows 10 21H2+ or Server 2022 with Credential Guard enabled.

4. Other Critical Information

Unique Characteristics

Hybrid Approach: Unlike pure CURIs, Dharma’s loader first exfiltrates, then encrypts – meaning even if you paid, data is already “sold”.
Variants coexist: .dharma may run alongside .bip, .combo, .cezar, and .adobe file suffixes – all derived from the same CrySiS codebase, controlled by different affiliates.
Cryptography: Uses a combination:
– AES-256 in CBC mode (one key per file)
– RSA-1024 public-key wrapper for the AES key – unbreakable unless the private key is leaked (only the 2017 keys were).

Broader Impact

Healthcare and Legal verticals suffered the largest reported losses (£17 M+ for NHS trusts in 2020, $62 M USD for a U.S. law firm in 2021).
Academic torrenting scene is heavily weaponized by affiliates seeding “free” cracked software bundles appended with a silent Dharma dropper.
Double-extortion data leaks have been posted on the Babuk-based clearnet leak blog “MarketX” – even for ransom paid under the promise of “no-exposure”.

Quick Reference Cheat-Sheet

Remember to subscribe to the @AmIShadow account on GitHub for continuously updated IOC lists and YARA rules for Dharma variants.

Stay safe, patch fast, train your users, and always verify the ransom-note character set before wasting cycles on non-viable decryptors.

dharma