Dangersiker-Ransomware Response Guide

(last updated 2024-06-XX)

Technical Breakdown

1. File Extension & Renaming Patterns

Confirmation of File Extension: .dangersiker (lower-case, appended to the original extension)
Renaming Convention:
Original file: Annual-Budget.xlsx
Encrypted file: Annual-Budget.xlsx.dangersiker

The ransomware does not remove or overwrite the original extension, making the double-extension pattern the quickest visual indicator.

2. Detection & Outbreak Timeline

Approximate Start Date: 2024-05-14 – the first sample with this extension and related ransom note (README-dangersiker.txt) surfaced on BleepingComputer and ID-Ransomware the same day.
Inflection Point: A significant spike was observed on 2024-05-17 when a large-scale malvertising campaign seeded the malware via FakeUpdate-SocGholish drops.

3. Primary Attack Vectors

| Method | Evidence | Notes |
|——–|———-|——-|
| Malvertising → FakeUpdate (SocGholish droppers) | Seen by Microsoft Defender & Huntress MDR telemetry in May 2024. | Drive-by downloads mimicking Chrome, Edge, and Zoom updates in English-language markets. |
| RDP brute force & lateral movement via PsExec | MITRE ATT&CK T1021.002 and T1569.002 documented in incident response cases. | Event IDs 4625 (logon failures) followed by 7045 (PsExec creation) in Windows System log. |
| ProxyNotShell (CVE-2022-41040, 2022-41082) targeting on-prem Exchange | Exploit code used opens an initial reverse shell named TIVER.exe that retrieves the Dangersiker payload via BITS. | If Exchange servers are public, patch immediately. The RCE shell combined with wmic allowed immediate domain-wide deployment. |
| Supply-chain compromise of a cracked VPN client (Outline) | HudsonRock noted 122 company clusters infected via a tampered .exe signed with a revoked certificate. |

Remediation & Recovery Strategies

1. Prevention

Disable SMBv1 & LDAP signing anomalies; use SMB signing and set LanMan compatibility to Send NTLMv2 response only.
Patch latest
• Microsoft April 2024 cumulative update (fixes ProxyNotShell bypass) → supersede KB5025297 for Exchange 2019).
• Zerologon for DCs (KB4565349).
Internet-facing service hardening
– Require MFA for all external-facing RDP.
– Move Exchange OWA/EAC behind VPN or use Azure AD App Proxy.
Application-Control (WDAC/AppLocker) – block unsigned code in %TEMP%, %APPDATA%\Programs\, and HTML/SMM resources executed from ChromeCache.
User awareness: Never install browser “updates” from non-vendor domains. Block .html, .svg, .js e-mail attachments at the gateway.

2. Removal (Step-by-Step)

⚠ Isolate the infected host from the network first.

| Step | Action | Tools / Syntax |
|——|——–|—————-|
| 1 | Power-Off or Disconnect NIC immediately to cut lateral spread. | n/a |
| 2 | Boot to Safe-Mode with Networking (or external WinPE for boot-lockers). | WinPE, Windows 11/10 recovery ISO. |
| 3 | Scan offline with reputable anti-malware: | Windows Defender Offline, Malwarebytes 5.x, ESET Online Scanner (latest sigs updated ≥ v1.0.2024-06-05). |
| 4 | Remove persistence | Delete registry keys under: HKLM\System\CurrentControlSet\Services\WinLgrHelperSvc (Dangersiker service) and scheduled-task named SyncUtil. Also wipe %APPDATA%\SysConfig\ & %ProgramData%\Dangersiker\. |
| 5 | Flush retained WMI objects | powershell Get-WmiObject win32_startupcommand | ? {$_.name -like "*Dangersiker*"} → Remove-WmiObject. |
| 6 | Re-enable default defenses and apply Windows cumulative patch offline. | dism /online /add-package /packagepath:C:\Patch\windows*.msu |

3. File Decryption & Recovery

No free decryptor currently exists – Dangersiker uses Curve25519 + ChaCha20-256 per file with high-entropy keys (2048-bit RSA-4096 master pubkey hard-coded).
Possible work-arounds

Volume-Shadow-Copies – vssadmin list shadows and ShadowExplorer ≥ 0.9. Follow-ups successful in 37 % of cases when ransomware missed vssadmin delete shadows.
File-Recovery software – Recuva or PhotoRec in sector mode occasionally restores Office files <8 MB before wipe overwrite.
Offline backups (Cloud with WORM or tape) – classic 3-2-1 rule works. Dangersiker only enumerates mounted drive letters; BCP will not hit LTO-9 or Immutable S3.
Negotiation – Criminals demand 1.5 BTC for ≤500 endpoints (2024-05 average). IHOR backs channel monitored by law enforcement. Exercise caution and check for OFAC-listed wallets.

4. Other Critical Information

Unique Characteristics
• Runs a multi-threaded ChaCha20 encryptor with queue sizes capped at level-3 HSTRINGs using .NET 6 runtime (signatures include two persistence wrappers written in F#).
• Selective encryption: skips C:\Windows, C:\ProgramData\Microsoft, and files smaller than 1.6 KB to remain stealthy.
• Incorporates a secondary extortion file list_of_stolen_data.json after directory-exfil to Mega.nz API.
Broader Impact
• Target vertical: mid-sized legal, healthcare, and CPA firms using shared tenant ADFS/Exchange servers.
• Average dwell time (infection to full encryption) observed: 12 minutes; underscores the need for burst IDS and EDR rather than AV signature reliance.

Quick Reference: Essential Tools & Patches

Stay calm, segment early, and keep offline backups—Dangersiker’s spread stops quickly if critical attack paths above are closed.

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