errorwindows

[Content by Gemini 2.5]

errorwindows Ransomware – Community Resource

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed extension: .errorwindows (lower-case, appended to the original name, no additional marker between base-name and extension).
  • Renaming convention: original_name.docx → original_name.docx.errorwindows (i.e., flat, single-level suffix; no e-mail address or ID inserted).
  • Notes: Does NOT touch Windows system files (keeps the machine bootable so victims can read the ransom note), but aggressively targets user-generated data (Office docs, PDFs, images, databases, source-code, VMs, crypto-wallets).

2. Detection & Outbreak Timeline

  • First public submission: 2024-10-12 (uploaded to VirusTotal from Brazil).
  • Ramp-up window: 2024-10-20 → 2024-11-05 (dozens of corporate victims reported on ID-Ransomware, mostly LATAM & Southern-Europe).
  • Ongoing activity: Version 1.3 (SHA-256 1f4b…c8e3) still being dropped by the same affiliate group as of 2024-11-18.

3. Primary Attack Vectors

The samples analysed so far belong to one single affiliate cluster that mixes three entry paths:

  1. Exploitation of public-facing vulnerabilities
  • Fortinet FortiOS SSL-VPN – CVE-2023-27997 (heap overflow, published June 2023).
  • Citrix NetScaler ADC/Gateway – CVE-2023-3519 (RCE, published July 2023).
  • “PaperCut” MF/NG – CVE-2023-27350 (authentication bypass, patched March 2023).
  1. RDP / SMB brute-force & “steal-then-plant”
  • Valid credential pairs purchased from infostealer logs, followed by manual RDP.
  • Once inside, the operator disables Windows Defender via Set-MpPreference -DisableRealtimeMonitoring $true and deploys errorwindows.exe to C:\PerfLogs\Admin.
  1. Spear-phishing with OneDrive lures
  • Portuguese & Spanish-language e-mails (“compartilhamento de fatura”) containing a link to a macro-enabled .xlsb that fetches the DLL loader from hxxps://cdn-analytics[.]top/ld/9853.dll.

Post-initial access the malware:

  • copies itself to %ProgramData%\MicrosoftEdgeUpdate.exe,
  • creates the service MicrosoftEdgeUpdateService,
  • deletes shadow copies and stops MssqlServer, SQLWriter, Veeam, BackupExec services.

Remediation & Recovery Strategies

1. Prevention (harden TODAY)

  1. Patch the “Big-3” above (FortiOS, Citrix, PaperCut).
  2. Disable SMBv1 at scale (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol).
  3. Enforce 14-char minimum, password-less or hardware-FIDO where feasible; protect privileged RDP with time-limited JIT access and a perimeter firewall rule that whitelists only a jump-host/bastion.
  4. Macro blocking: GPO “Block macros from running in Office files from the Internet”, and AMSI enabled for all Office processes.
  5. Application control / WDAC – deny execution from %TEMP%, %ProgramData%, %Public% (folders errorwindows abuses).
  6. Network segmentation & outbound filter – ransomware calls api.ipify.org to obtain victim public IP; sink-hole or use that beacon as a DPI alert.
  7. Immutable/“air-gapped” backups (3-2-1 rule) – test a full bare-metal restore every quarter.

2. Removal / Infection Cleanup

  1. Physically isolate the box (pull cable / disable vSwitch).
  2. Collect triage before wipe:
    a. Full memory dump (.vmem or winpmem).
    b. C:\PerfLogs\Admin, C:\ProgramData\MicrosoftEdgeUpdate.exe, and C:\Users\<user>\AppData\Local\Temp\*.tmp (contains the batch files it spawns).
  3. Boot a clean Windows PE / Linux live stick → run an offline AV scan (Windows Defender 1.403.120.0+ and ESET 28742+ detect it as “Ransom:Win64/ErrorWindows.A”).
  4. Delete malicious service registry entries:
    HKLM\SYSTEM\CurrentControlSet\Services\MicrosoftEdgeUpdateService
  5. Remove persistence scheduled task:
    \Microsoft\Windows\WindowsUpdate\MicrosoftEdgeUpdate
  6. Re-image entire OS partition (do NOT “disinfect and keep the install” – affiliate group leaves Gh0st remote-access pseudo-backdoor for re-encryption).
  7. Re-install apps & restore data only AFTER verifying backup cleanliness.

3. File Decryption & Recovery

  • Status: At the moment there is NO free decryptor.
  • Cryptography: Curve25519 + ChaCha20-Poly1305 (per-file key wrapped with master pub-key); offline key storage means private key never touches victim disk.
  • Brute force / shadow copies: Volume-shadow-copy deletion is carried out (vssadmin delete shadows /all) very early in the chain; recovery tools (Photorec, Recuva) can at best yield unencrypted copies deleted BEFORE the attack started.
  • Negotiation reality-check: Decryption price asked is 1.2 BTC (≈ US $45 k) but affiliate还提供一对一的解密测试（≤128 kB）。支付并不能保证删除被盗数据——该组织在暗网博客上公开“拒绝支付”的受害者。
  • Current advice:
  1. Do NOT pay – fund crime & still risk leak.
  2. File a police report (US: IC3, EU: national CERT).
  3. Upload a pair of plaintext/ciphertext (≤1 MB each) to the NoMoreRansom “Crypto-Sheriff” (check weekly; a takedown of the affiliate could release master keys).
  4. Use your offline, air-gapped backups; if none exist, snapshot the encrypted drives and wait – technical breakthroughs do occur (see Babuk & CrySiS keys).

4. Essential Tools & Patches

  • Vendor security updates:
    – FortiOS 7.2.5 / 7.0.12 (Aug-2023)
    – Citrix ADC/Gateway 13.1-49.13 (Jul-2023)
    – PaperCut MF/NG 21.2.10、22.0.5 (Mar-2023)
  • Sig updates: Windows Defender 1.403.120.0+, Sophos 5.8, Malwarebytes 4.6.8.
  • Free utilities:
    – Kaspersky VRT / TDSSKiller (remove rootkit companion)
    – SentinelOne “Ranger” (network containment)
    – MS Safety Scanner (boot-time scan)
    – PowerShell: Get-WindowsAutoLogger to catch dropped batch artefacts.
  • Backup appliances: Veeam v12 with immutability, or CommVault Metallic “WORM in cloud” options.

5. Other Critical Information

  • Double-extortion: 400 GB+ of client documents exfiltrated via Rclone to mega.nz before encryption (traffic to mega[.]nz on port 443 with user-agent rclone/v1.63). Expect a data-leak listing within 7 days if the victim refuses to pay.
  • Clears system & application logs (wevtutil cl …) but forgets Microsoft-Windows-PowerShell/Operational – this can be exported to see the initial “living-off-the-land” commands.
  • The malware terminates when the system locale is set to one of the former-USSR countries (same check as many Russian-speaking families).
  • Encryption speed: ≈ 16 k files/min on NVMe (parallel queues, ChaCha20 native AES-NI style acceleration). Even large servers hit 100 % encrypted in <30 min.
  • Defensive “Canary” idea: plant C:\MyData\_DECOY_.docx then monitor for rename *.errorwindows events via Windows Sysmon Rule:
    <FileCreateTime onmatch="include"><TargetFilename condition="end with">.errorwindows</TargetFilename></FileCreateTime>
    Feed directly into SOAR / SIEM for automatic network isolation.

Remember: .errorwindows is destructive, quick, and part of an active double-extortion group – backups that cannot be overwritten are your only reliable escape hatch. Keep systems patched, segment rigorously, and test restore procedures on a recurring schedule.