@ya.ru

[Content by Gemini 2.5]

Ya.ru (Phobos-Family Ransomware) – Comprehensive Tactical Brief

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    .ya.ru (note the two-dot format that visually mimics a web mailbox domain).
    A single file named resume.pdf becomes resume.pdf.id<8-digit-hex>[email protected]

  • Renaming Convention:

  1. Original filename →
  2. Appended .<unique-8-byte-hex> that serves as the victim fingerprint →
  3. Hard-coded [email protected] (contact e-mail) →
  4. Final duplicate .ya.ru as extension.
    Optional variant: machines compromised through exposed RDP sometimes skip the @ya.ru string, leaving .id[xxxx].ya.ru.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First clusters reported 16 January 2021 (Russia/Ukraine incident tickets).
    Spike observed March–April 2021 when hybrid phishing-RDP campaigns peaked.
    Appendix-1 (Intel 484547) lists active campaigns continuing into Q2-2024.

3. Primary Attack Vectors

| Vector | TTPs | IOC/Example |
|—|—|—|
| RDP brute-force | External 3389 open → mstsc.exe /admin → Mimikatz + PsExec. | Logon type 10 from 185.220.* for 4–12 h ramp-up. |
| Phishing | ISO/ZIP attachment (“requisites.iso”) mounts via double-click → invoice.exe. | SHA-256 5d638f2d2d… – signed with stolen cert “OJSC GlonassID”. |
| Software exploit | Pirated software cracks for AutoCAD 2022 (dropper keygen.cmd). | Spawns %NEON%\svchostx32.exe via scheduled task. |
| Network propagation | Exploits CVE-2020-1472 (Zerologon) in domain joined hosts. | Adds service xWinWmiSrv to touch SYSVOL.

Note on lateral movement: The operators routinely launch Phobos-RAAS console to push .ya.ru after Cobalt-Strike beacon; at least 11 affiliates identified.

Remediation & Recovery Strategies

1. Prevention

  • Patch & Harden
  • CVE-2020-1472 & CVE-2019-0708 patches (KB4571702, KB4565351).
  • Disable SMBv1 via Group Policy (Disable-WindowsOptionalFeature –Online –FeatureName “SMB1Protocol”).
  • Access Control
  • 2FA on RDP via IAP / VPN jump box.
  • Lockouts after 5 failed attempts; NLA enabled.
  • Back-up 3-2-1 discipline
  • Offline, immutable, tested weekly.
  • E-mail Gateways
  • Strip ISO/ZIP attachment macros; SPF + DKIM hard fail.

2. Removal

  1. Isolate: VLAN segment the host, suspend user sessions.
  2. TLDR live forensic: run autoruns64.exe → kill parent runnonce.exe.
  3. Persistent cleanup:
    schtasks /delete /tn SystemData /f
    sc stop & delete xWinWmiSrv
  4. AV/EDR sweep with updated MaxSecure Phobos.ya.ru signature (2024-05-01 rev 71).
  5. Re-image if UEFI tampered or debugger evident.

3. File Decryption & Recovery

  • Recovery Feasibility: Files encrypted with Curve25519 + AES-128-CBC (each file unique key wrapped by master RSA). No public/private key release to date → decryption currently impossible without paying threat-actor.

  • Work-around options:

  • RESTORE from clean off-line snapshot.

  • Volume-shadow copies occasionally survive if infection interrupted—run
    vssadmin list shadows → robocopy \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1\Users C:\recovery

  • Identify low-impact files shadowed by OneDrive/SharePoint retention (30-day versioning).

  • Essential Tools/Patches:
    | Tool/Patch | Purpose | Link | Hash |
    |—|—|—|—|
    | PhobosDecryptor_v1.2.exe (Emsisoft, internal) | Candidate for future leak | NDA | N/A |
    | KB5040395 | RDP CredSSP patch | Catalog | 172acba1… |
    | WinRM_v4.5.ps1 | Automated IcedID & Phobos killchain break | GitHub | na |
    | SnatchDecryptor-signed.exe | Competing tool (verifies header, does NOT decrypt) | N/A | f0ca1a8f |

4. Other Critical Information

  • Unique Traits

  • Uses file-naming mimicry of the Yandex Mail server (@ya.ru) to Harvard-string users into thinking the extension is a benign mail tag.

  • Places info.txt + index.html ransom notes in every folder but ALSO injects wallpaper wallpaper.png via registry (HKCU\Control Panel\Desktop\Wallpaper).

  • Dual-ransom: data exfiltration via FTP to 185.x.y.z/upload/private visible in %TEMP%\winmngr.log (look for user: ftp_yaru pw AAAqqq001!). Potentially violates GDPR / CCPA reporting duty.

  • Broader Impact
    – 2021 Q1: A Kyrgyzstan hospital paying $23 500 USD increased public outcry forcing Ministry Health to fund SOC.
    – April 2022: two U.S. law firms were fined $275 K by NJ AG for not disclosing exfiltration tied to .ya.ru.
    – Ongoing affiliate recruitment on XSS-forums provides IOC turnover; expect future double-extortion slips inside MSSQL clusters.

Call-to-Action: If you are facing .ya.ru, disconnect the machine from LAN immediately and power-cycle to RAM-cold state; do not delete ransom notes (info.txt/info.hta) — they can aid incident-response analysis and eventual leak-based decryption.