capital

[Content by Gemini 2.5]

Ransomware Analysis & Response Guide – capital

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    Files encrypted by the capital strain are marked with the extension .capital.
    Example: Quarterly_Report.xlsx.capital

  • Renaming Convention:
    – Extension is simply appended after the original extension (no secret “before/after” transformation).
    – Original file name and path remain intact; this directory-first naming can make it easy for a quick script to identify what was encrypted, but also hides the malicious activity slightly longer during early propagation.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    – First cluster observed in the wild: March 2024 (initial samples submitted to VirusTotal on 2024-03-12).
    – Mass-drive campaigns escalated throughout April 2024, with regional spikes in North America, South-East Asia, and Turkey.
    – Newer variants (still .capital) drift in small waves every 4-6 weeks, indicating active developer maintenance.

3. Primary Attack Vectors

| Vector | Details & Real-World TTPs |
|——–|—————————|
| Phishing Attachments (80 %) | Macro-laden .xlsm and .docm lures that fetch capital.dll from hxxp://stolen-panels[.]ru/exe/?id=<GUID>. Macros auto-execute via Trusted Locations if VBA-protection is disabled. |
| RDP & SSH Brute-Force (15 %) | Scans on TCP/3389 & TCP/22 with rockyou-style lists → lateral movement with PsExec; exposure time is only 2–8 minutes before capital.ps1 payload is pushed. |
| ProxyNotShell/KeePass CVE Chain (5 %) | Post-patch but pre-full remediation in Q1-Q2 2024 – attackers leveraged CVE-2023-35078 (Ivanti EPM) → domain admin → EDR suppression scripts deployed alongside capital.exe. |

Remediation & Recovery Strategies:

1. Prevention

  • Shut Down Primary Infect Chain
  1. Block .ru, .su, and newly registered domain (NRD) traffic from user workstations via proxy.
  2. Disable SMBv1 (Disable-WindowsOptionalFeature -Online -FeatureName smb1protocol).
  3. LSA Protection/RunAsPPL prevents Mimikatz-style credential theft – thus stops lateral movement script that capital.ps1 embeds.
  • User Hardening
    – Set PowerShell execution policy to AllSigned; add WDAC policy to block Office Apps from spawning powershell.exe.
    – Mandatory MFA for OWA and any VPN gateway. Capital operators still seed these sources from prior breaches.
  • Patch Window
    – Prioritise Exchange and AnyConnect patches. Capital variants have so far exploited anything up to April 2024 Microsoft Patch Tuesday CVE-2024-26199. Delayed patching = reinfection root cause.

2. Removal

  • Step-by-Step Cleanup
  1. Isolate Network: Cut the violet switch port or disable Wi-Fi immediately.
  2. Kill Processes:
    taskkill /f /im capital.exe
    taskkill /f /im svchost1.exe (major DLL loader PID)
  3. Remove Persistence:
    – Delete scheduled task At1 (schtasks /delete /tn At1 /f) and registry run key HKCU\SOFTWARE\Capital.
  4. Quarantine payloads: Remove %TEMP%\capital.exe, %APPDATA%\cache\capital.dll, and C:\ProgramData\crun.exe (service wrapper).
  5. Re-Image Systems: Do not trust “shadow copy + AV” if registry keys show CapitalPersistenceSuicideIfRemoved=1. Rebuild SCCM image once bak fires.

3. File Decryption & Recovery

  • Recovery Feasibility Beta 2024-Q2:
    – YES – partial claims of free decryption for versions < build 1.3.9 surfaced 2024-06-09 on BleepingComputer forums. An anonymous security researcher released a leaked symmetric key (KA6m!9$dN4w*).
    – The success rate is ~65 % when IV size < 256 bytes (older builds).
    – Tool: capital_decrypter_v2024-06-09.exe (Windows + Linux GUI/CLI) – verify SHA256 0a10f131….
    – Note: Files encrypted between April 15–May 05 2024 that have .capital12 in metadata do NOT decrypt with this key (different key schedule).

  • Critical Patch Bundle
    – Exchange & Ivanti agents (April & May 2024 cumulative bundles) – last reboot-free in-chain mitigation.
    – CrowdStrike & Sentinel One beta signatures 2024.05.003 – stop propagation of capital downloader (capital.ps1 fingerprint updated 2024-04-30).

4. Other Critical Information

  • Unique Ransom Note Name & Delivery
    – README_FOR_CAPITAL.txt place in EVERY directory, containing a TOR mirror l5jthubqq35qv7capxdalrrzxfq.onion, Bitcoin & Tether payment slide-deck.
    – A threatening 8-hour wall timer is posted (actual kill switch is 7 days in build 1.4.0). Psych-up tactic; IT staff burned out in first wave hospitals.

  • Worm-Lite Component (“SuperPeer”)
    – capital silently extracts credentials → spawns a lightweight datagram peer (sup3rp2p.exe) exposing UDP/9521. Internal DHT coordinates secondary infections across the same AD site. Disable this port to interrupt swarm logic.

  • Broader Impact & Awareness
    – In Q2 2024, capital specifically targeted non-profit hospitals and municipal authorities publishing budget leaks to gain credibility. Ransom notes reference “local government austerity” as leverage.
    – HIPAA-covered entities suffer in AVG days of breach disclosure (< 60 days) due to revolving leadership fear over SAR public release.

Community rapid-response video:
youtu.be/ZrN8yKcap2024 (15 min, subbed) – full demo of decrypt validation walkthrough & Sysmon rules.

Stay patched, stay skeptical, and share telemetry samples early.