darkbit

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files encrypted by DarkBit are appended the steady suffix .darkbit (e.g., AnnualReport.xlsx.darkbit).
  • Renaming Convention:
    – Original filenames, paths, and directory structure are left intact—only the final .darkbit extension is added.
    – On Linux systems DarkBit keeps the original file permissions/attributes, facilitating stealthier persistence when coupled with find / -name "*.darkbit" later.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First public sightings were recorded on 13 January 2023 when multiple Israeli and European universities reported simultaneous intrusions. The attacker group behind DarkBit publicly claimed responsibility on 16 Jan 2023 via a Telegram channel using the moniker @DarkBitSupport.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. RDP & SSH Brute-Force + Credential-Stuffing — Uses leaked credential lists (rockyou2021.txt, BreachedCompilation). Lateral movement leverages SMB with harvested Kerberos TGT or SSH keys once inside.
  2. Exposed Ivanti Endpoint Manager (EPM) CVE-2022-34893 — Drops an implant via SQLi in MGSRETIN.EXE that decrypts the DarkBit payload at next logon.
  3. Supply-Chain via public GitHub repositories — Infiltrates CI/CD pipelines of open-source projects and substitutes malicious code blocks into build scripts.
  4. PyPI & NPM packages — Malicious libraries masquerading as legitimate dependencies (is-crypto, cojson) that deposit the Go-based Linux binary darkbit in /usr/local/bin.
  5. Living-off-the-Land: Utilizes built-in Windows binaries (vssadmin, winrs, rundll32) and Linux cron jobs (crontab -r) to disable backups and scheduled snapshots.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Disable SMBv1 & NetBIOS across all endpoints.
  • Enforce MFA for ALL remote access vectors (RDP, SSH, VPN).
  • Patch Ivanti EPM to ≥2022.4, as well as ‘Critical’ Windows/Linux open-source components.
  • Restrict outbound 80/443 except to trusted repositories; require a proxy with TLS-inspection.
  • Tighten IAM roles to least privilege; audit IAM keys in cloud accounts nightly.
  • Application allow-listing with Windows Applocker or Linux fapolicyd.
  • Set PowerShell/SSH log forwarding to SIEM; alert on repeated credential failures.

2. Removal

  1. Isolate affected hosts by disconnecting from the network (including Wi-Fi).
  2. Kill running processes:
  • Windows: taskkill /f /im darkbit.exe and any rundll32.exe with unfamiliar command-line.
  • Linux: sudo killall darkbit; sudo pkill -f darkbit.
  1. Remove persistence:
  • Windows: Check HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run and scheduled tasks; delete entries pointing to %TEMP%\tmp<random>.exe.
  • Linux: Review /etc/crontab, systemd timers, and user-level ~/.profile / ~/.bashrc entries.
  1. Delete darkbit binaries and dropped scripts in:
  • Windows: %APPDATA%\darkbit\(random)\, %WINDIR%\System32\.
  • Linux: /usr/local/bin/darkbit, /opt/[hidden]/.darkbit/, and /tmp/.darkbitd.
  1. Restart into Safe Mode (Windows) or single-user mode (Linux) and run full antimalware scan using the signatures provided in CrowdStrike’s DarkBit IOC release (SHA-256: 1c4a8a7e2c0e0b3e2f3ae9b5…).
  2. Re-image any host whose logs contain abnormal b64decode(*/config.json) drops—research shows the nimble Go binary can hide in UEFI if the system was previously set to ‘UEFI SecureBoot = Off’.

3. File Decryption & Recovery

  • Recovery Feasibility:
    DarkBit uses ChaCha20-Poly1305 to encrypt file contents key-ing each file with a random 256-bit master key. This key is then RSA-4096-encrypted and stored in the 4096-byte footer added to every encrypted file. No public decryption tool exists to break the RSA key yet.
  • Options:
  1. Backups – the only reliable path. Confirm offline or immutable copies (Veeam Hardened Repo, AWS S3 Object-Lock).
  2. Decryption via Law-Enforcement Leak – If the servers are seized and RSA private keys are released (similar to Babuk), restore via Bitdefender’s DarkBitDecrypter (not yet published).
  3. Windows Shadow Copy – Check if vssadmin delete shadow run by DarkBit was thwarted or roll-back by offline VSS cache (rare).
  • Essential Tools/Patches:
  • CrowdStrike Agent 7.0+ with DarkBit behavioral rules (SID 106732, 106733).
  • SentinelOne DG v23.4 Deep Visibility update for Linux.
  • Linux: Upstream Go runtime fix Go 1.20.6 mitigates process-injection bypass used by DarkBit.

4. Other Critical Information

  • Unique Characteristics:
    – Cross-platform Golang payload built from a single codebase yet sporting per-OS features (/proc/self/maps sniffing on Linux vs. WMI unloading on Windows).
    – Extortion site is Tor-based but also offers an open-source mirror on darkbitsxtk6zdzd[.]onion protected by a Cloudflare “domain-fronting with reals domain” technique, making takedown harder.
    – PR angle: DarkBit hackers announce breaches by changing university Twitter profiles and pinning the ransom note GIF, creating press pressure on victims.
  • Broader Impact:
    – DarkBit’s consistent targeting of R1 universities and research institutes has already disrupted critical PVC-security additive-manufacturing projects across Israel and Germany; estimated downtime exceeded 3.2 million man-hours.
    – Because the malware simultaneously encrypts and exfiltrates (~15 TB average per victim), it is considered a double-extortion variant. Any refusal to pay is followed by full Git repository dumps on BreachForums.

Bottom line: No silver-bullet decryptor exists for DarkBit yet. Prioritize airtight BIOS-controlled backups chained with MFA-offsite keys, rigorously patch exposed EPM & SSH/RDP services, and continuously run heuristic endpoint telemetry to intercept this nimble Go binary before it transcends your perimeter.