[email protected]

[Content by Gemini 2.5]

Comprehensive Guide: [email protected] (LockerGoga) Ransomware

Technical Breakdown

1. File Extension & Renaming Patterns

  • Extension used: .locked (many variants add the e-mail address in a separate ransom note, not in the filename)
  • Renaming convention:
  1. Original files are overwritten (not simply renamed).
  2. The resulting file keeps the original name plus .locked appended → Document.docx.locked.
  3. No additional UID or victim-ID folder prefix; directory structure remains intact.

2. Detection & Outbreak Timeline

  • First sighting in-the-wild: March 2019 (collection of hashes uploaded to VT).
  • Major public incidents:
  • Norsk Hydro (March 2019) – operational networks, ICS.
  • Altran Technologies (April 2019).
  • Various Asia/Europe manufacturing plants detected in May–October 2019.

3. Primary Attack Vectors

LockerGoga rarely uses e-mail spam. Observed infection chains:

  1. Credential-oriented access:
  • Brute-force or previously-stolen credentials for corporate RDP / VPN services.
  • Lateral movement inside network via PsExec, Cobalt Strike, WMI.
  1. Living-off-the-land privilege escalation:
  • Local exploit or sticky-keys backdoor to gain SYSTEM.
  1. Manual deployment:
  • Interactive operator stops antivirus services (net stop lists of service names).
  • Batch script or scheduled task staging the binary (lockergoga.exe or task[xx].exe).
  1. N-day toolkits: No evidence of mass exploitation bugs like EternalBlue; LockerGoga relies on stealing valid access first.
  2. Signed malware: Windows driver-style code-signing certificates used to evade early whitelisting.

Remediation & Recovery Strategies

1. Prevention

| Action | Rationale | Tool / Policy |
|—|—|—|
| Disable RDP open to Internet / enforce VPN + MFA | Majority of intrusions start here | Firewall ACL + MFA on VPN/RDP authentication |
| Use LAPS & unique, complex local admin passwords | Stops lateral movement via hash reuse | Microsoft LAPS |
| Segmentation of OT & IT networks | Limits ransomware leap into production | ISA/IEC 62443 zoning |
| Disable user-level AD accounts with “WriteOwner” over DCs | Blocks attacker from elevating to Domain Admin | BloodHound/AGDLP review |
| Patch third-party apps and OS to current versions | Reduces secondary leverage vectors | WSUS / Intune / SCCM |
| AppLocker or Windows Defender ASR rules | Blocks unsigned binaries from non-approved paths | Defender ASR Rule “Block execution of potentially obfuscated scripts” |
| Enable tamper protection on AV; restrict local service stop rights | Prevents the usual manual shutdown of defenses | GPO – “Deny interactive logon” + tamper protection registry flags |

2. Removal (if system is cleanable)

Because LockerGoga overwrites files irreversibly, ransomware files themselves are easy to wipe—the challenge is preventing one infected node from re-deploying the executable.

Step-by-step:

  1. Isolate: Physically cut power or disable NIC on all suspect machines.
  2. Image before any cleaning for forensic trace-back.
  3. Boot to safe mode without networking.
  4. Find & delete dropped components:
  • %TEMP%\task##.exe
  • %WINDIR%\System32\lockergoga.exe (signed, but SHA-256 differs per campaign)
  • Registry run keys in HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System (Shell or RunOnce).
  1. Kill persistence:
  • Disable built-in administrator and any new local accounts (check lusrmgr.msc).
  • Remove rogue scheduled tasks in %WINDIR%\System32\Tasks\.
  1. Patch credentials: Reset all domain service accounts; rotate local admin passwords via LAPS.
  2. Scan the image with an offline AV engine to confirm no residual signed dropper.

Run a full domain-wide sweep with EDR capable of detecting process hollowing, WMIC abuse, and Cobalt Beacon.

3. File Decryption & Recovery

  • Decryptable? No. LockerGoga uses a secure AES-256 key wrapped with a generic (per-campaign) RSA-1024/2048 public key. No known master private key has been released.
  • Recovery paths:
  • Restore from offline backups on WORM media or cloud immutable snapshot (Azure Blob, AWS S3 Object-Lock, Veeam hardened repository).
  • Volume Shadow Copies are purged (vssadmin delete shadows /all /Quiet) automatically—check before removal.
  • Essential tooling: Emsisoft’s LockerGoga Check-Tool only verifies if a file was encrypted with the original keyset—it does not decrypt.

4. Other Critical Information & Notable Characteristics

  • Unique behaviors:
  • Attempts to uninstall AV products by GUID enumeration.
  • Uses code-signing fraudulently stolen from MEGASOFT NY (previously revoked).
  • Native aggressive disabler of Intel/AMD hardware breakpoint registers to thwart emulation.
  • Enterprise twist: Operators set a text file README-NOW.txt (or README_LOCKED.txt) containing a simple signature line: “[email protected]” followed by the ransom 0.1–0.5 BTC price and a wallet ID that frequently changes.
  • Post-mortem advice:
  • Build recovery-runbooks that assume both DCs and backup server may be compromised.
  • Record both SHA-256 and code-signing certificate fingerprints to retroactively hunt for any re-introductions using older signed binaries.

Bottom line: [email protected] LockerGoga is a manually-deployed, enterprise-grade ransomware whose payload is devastating. It usually reaches mission-critical networks—think hydropower, chemical plants—via compromised credentials. The best “cure” is never letting it start; once encryption completes, offline backups remain the only reliable recovery lever.