cspider

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: CSPIDER appends “.cspider” to every file it encrypts, preceded by a short numeric ID in square brackets.
    Example: annual-report_2023.pdf.[№113267].cspider

  • Renaming Convention:
    The malware preserves the original filename + original extension, adds a space, inserts the victim-ID in brackets [№xxxxx], then appends .cspider.
    Folders themselves are NOT renamed; however, a ransom note named READ_ME_DECRYPT.txt (or occasionally RESTORE_FILES.html) appears in every encrypted directory.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First clusters appeared late June 2023. Campaigns ramped up throughout July and August 2023, primarily targeting North- & South-American mid-size manufacturing, legal, and retail verticals. Activity continues into 2024 with geographically separated waves (APAC observed in late February 2024).

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Compromised Remote Desktop Protocol (RDP) – brute-force or purchased credentials, then lateral movement with PSExec/RDP.
  2. Phishing (DocuSign & SharePoint lures) – macro-enabled Office or ISO attachments that invoke PowerShell to pull the dropper.
  3. Exploitation of ProxyShell/ProxyLogon – where unpatched on-prem Exchange servers still exist.
  4. Software supply-chain footholds – targeting MSP-supplied remote-agent software (ConnectWise ScreenConnect, AnyDesk) when not updated.
  5. Chained SMB – if the initial box is running SMBv1 and EternalBlue was not yet patched, Cobalt-Strike beacon propagated laterally.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Discontinue any use of SMBv1; enforce SMB signing.
    • Apply the latest cumulative Windows patches (especially MS17-010, April 2021 Exchange CUs, June 2023 security monthly).
    • Enforce Network Level Authentication (NLA) on every exposed RDP endpoint; require MFA and strong, unique passwords.
    • Segment flat networks; isolate DCs and SQL from endpoints.
    • Require macro and ISO blocking via Group Policy (Settings → Macro → Block internet macros; Configure “Mark-of-the-Web”).
    • Roll out EDR/XDR with PowerShell command-line logging + ATA (Microsoft Defender for Identity, Sentinel).
    • Enable controlled folder access (Windows 10/11) to protect default document locations automatically.

2. Removal

  1. Disconnect the infected host from the network (pull cable / disable Wi-Fi / isolate VLAN).
  2. Boot to Windows Defender Offline Mode or boot WinPE/USB containing reputable offline scanner (Sophos, Kaspersky, Bitdefender).
  3. Quarantine or delete the persistent payloads (commonly dropped in C:\ProgramData\CS-WebCrawler or %PUBLIC%\csprdr.exe).
  4. Delete scheduled tasks and run keys:
    • HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run → CSpiderSync
    • C:\Windows\System32\Tasks\CSOnlineScan
  5. Clean up: Use Autoruns (Sysinternals) to scrub boot executables, services, and WMI event subscriptions. Clear Shadow Copies only AFTER confirming files are restorable from a clean backup.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • Decryption impossible (as of June 2024): CSPIDER uses AES-256 in CBC mode with keys encrypted by an RSA-2048 public key stored in the binary. The private key has never been seized or leaked. No viable flaw has been found.

    • Work-arounds: There is currently no free decryptor. Victims must rely on backups:
    ‑ Offline/off-site copies that were not reachable by the compromised admin account.
    ‑ Cloud object storage with immutable/WORM buckets.
    ‑ Test bare-metal restore to ensure tapes or images are intact.

  • Essential Tools/Patches:
    – Latest Windows patch rollups.
    – Microsoft Defender Antivirus signature ≥ 1.395.1705.0 (detects generations “Trojan:Win32/CSPDR.Impl”).
    – For Exchange: March 2023 Security Update, or move to Microsoft 365.

4. Other Critical Information

  • Unique Characteristics:
    • Partial encryption: Aims to reduce performance impact while breaking backups; first 10–20 MB and every 10th megabyte thereafter (depends on total file size). This makes forensic carving of unencrypted portions harder.
    • Time-bomb behaviour: On machines matching Russian or Belarusian keyboard layouts, the malware silently uninstalls itself, suggesting creators are Russian-speaking or wish to avoid Kremlin scrutiny.
    • Custom OT targeting: Detects if industrial controllers (Rockwell, Schneider) are installed and deliberately skips encryption on PLC/HMI files to avoid immediate production shutdown; reduces IT alert velocity but keeps pressure on management.

  • Broader Impact:
    CSPIDER is part of the same “Hunter-SPIDER Group” cluster associated with the adversary LOCKBIT 2.0 affiliates. Intelligence indicates CSPIDER is used as a secondary monetization layer after credential marketplaces have been exhausted. Compared with Ryuk or Conti, average ransom demand is lower (USD 35 k–70 k), but final negotiations frequently inflate due to threatened publication on “Dark-nest” DLS (Dark-data leak site) unless paid in full.

    Insurance providers are treating CSPIDER as a sub-scenario of LockBit, leading to reduced payouts unless MFA and segmentation were demonstrably in place before incident.

Remain vigilant: continue patch cycles daily, audit RDP/VPN logs weekly, and rehearse offline-restore scenarios quarterly.