desktoposiris.*

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files encrypted by DesktopOSiris (a.k.a. Osiris) receive the extension .osiris (written in lower-case, never highlighted by parentheses or brackets).
  • Renaming Convention: Each file is renamed according to the pattern
    OriginalFileName.[OriginalExtension].[unique-6-char-ID]-[unique-6-char-ID].[attacker-e-mail#1].osiris
    Example: [email protected]

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Campaigns delivering “.osiris” variants were first observed en-masse mid-June 2017, shortly after the end of the “Locky” .diablo6 wave. Activity continues intermittently, with resurgences peaking every 3–4 months. (Information updated: June 2024)

3. Primary Attack Vectors

  • Propagation Mechanisms:
    • E-mail phishing: Office macros inside bogus DocuSign, UPS, or Office 365 messages spread the downloader notRansomwareOsiris.exe.
    • EternalBlue / BlueKeep (smb-v1); worm-like lateral movement through un-patched Windows 7/Server 2008 R2.
    • RDP brute force – dictionary attacks against weak credentials on exposed TCP/3389.
    • Malicious Google Ads / malvertising leading to exploit kits (RIG EK, Fallout).
    • Targeted supply-chain compromise of MSP/ISP WSUS auto-update scripts (rare but documented).

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Patch immediately: MS17-010, CVE-2019-0708 “BlueKeep”, CVE-2020-1472 (Zerologon).
    • Enable and hard-code SMBv1 off (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol).
    • E-mail hygiene: block macro-laden attachments, strip .hta .js .vbs .wsf files at gateway.
    • Multi-factor authentication (MFA) on ALL remote desktop / VPN access.
    • Deploy AppLocker policy enforcing ONLY digitally signed executables.
    • Maintain offline + in-cloud immutable backups (e.g., Azure Immutable Blob).

2. Removal

  • Infection Cleanup (step-by-step):
  1. Physically isolate or disable all network cards; avoid reboots that trigger boot-sector encryptors.
  2. Collect volatile evidence (RAM forensic dump) if incident-response procedure demands.
  3. Boot from a trusted, read-only USB → run official “Locky + Osiris removal” scanner:
    ESETOnlineScanner.exe --malware-clean.
  4. Erase or format C:\Users\%USERNAME%\AppData\Roaming\*locky*, %TEMP%\*.exe.
  5. Remove persistence keys:
    – HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run → [dll_name].dll
    – HKLM\SYSTEM\CurrentControlSet\Services\QVMNetwork (boot-type 0x1).
  6. Change actively-used passwords enterprise-wide (it drops Mimikatz modules).

3. File Decryption & Recovery

  • Recovery Feasibility: No working free decryptor exists (June 2024). File keys are AES-256-CBC generated per machine and uploaded to the attacker C2 before deletion.
  • Essential Tools/Patches:
    – Kaspersky RannohDecryptor (supports most LOCKY flavours except .osiris 2017-2024).
    – Use instead Shadow-copy restore plus backup validation: vssadmin list shadows, or ShadowExplorer.
    – In place of decryption, repair broken NTFS MFT: run chkdsk /f /r /x if boot-sector not overwritten.

4. Other Critical Information

  • Unique Characteristics:
    • DesktopOSiris does not append itself to executables in %WINDIR%—it explicitly avoids touching EXEs to stay stealthy for a time.
    • Tor Hidden Service onion (“ 7yipb53ljjfss3x7m.onion ”) double as RSA public-key synchronization and live-chat “support.”
    • Uses mutex “Global\0C560543657A4AEE” to guarantee single-instance execution—detection hook possible.
  • Broader Impact: Because Osiris is branded by some groups as a “businses-grade double extortion” kit, attacks often exfil data first using ransomware-as-a-service (RaaS) before encryption. Expect extortion e-mails threatening GDPR fines (Europe) or other compliance breaches.

Bottom line: Treat “.osiris” ransoms as definitively non-decryptable and enact offline, verified backups plus swift isolation as the only sure-fire path to recovery.