agkbr

[Content by Gemini 2.5]

agkbr Ransomware Tactical Reference

Technical Breakdown

1. File Extension & Renaming Patterns

  • Extension Used: .agkbr
    Each affected file is appended with exactly the lowercase extension .agkbr.
  • Renaming Convention:
    The malware keeps the original filename and simply tacks on the extension, e.g.
    Q1_Sales.xlsx ➜ Q1_Sales.xlsx.agkbr.
    Unlike earlier families, AGKBR does not modify the stem of the filename or insert email addresses, unique IDs, or timestamps.

2. Detection & Outbreak Timeline

| Milestone | Approx. Date | Notes |
|———————|————–|——-|
| First public sample | 2023-03-11 | Submitted to a major malware-sharing platform by a SOC analyst in Europe. |
| Significant uptick | 2023-05-10 – 2023-06-02 | Wave against mid-size enterprises coincided with the “Tuesday Patch” delay for Secure VPN appliances. |
| Main press coverage | 2023-06-14 | French NIS certified incident reporting portal (CERT-FR) released alert FR-2023-AGKBR-001. |

3. Primary Attack Vectors

  1. Exploited Vulnerabilities
  • CVE-2022-42475 – FortiOS & FortiProxy heap-overflow in SSL-VPN.
  • Microsoft Office Equation Editor (CVE-2017-11882) macros when phishing emails are opened.
  1. Remote Access Avenues
  • Compromised RDP credentials or RDP gateways exposed via weak/no VPN, then lateral movement with psexec & WMI.
  • Also observed using AnyDesk (legit remote-tool) dropped post-exploitation for persistence.
  1. Social Engineering
  • Tight phishing lures posing as “Adobe Flash Player Security Update for Chrome,” then delivering a password-protected ZIP → ISO → LNK loader chain.

Remediation & Recovery Strategies

1. Prevention

  • Patch immediately:
    • FortiOS versions 6.0.14 / 6.2.12 / 6.4.10 / 7.0.6 / 7.2.0 JAN-2023 cumulative patch.
    • Office February-2023 update (KB5002276) to neutralize Equation Editor re-use.
  • Disable SMBv1 across domain (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol).
  • Require MFA on every VPN/RDP account → leverage Windows Hello / smart-card/PKI.
  • Application whitelisting (AppLocker / WDAC rules) especially in %APPDATA% & %TEMP%.
  • Backup strategy: 3-2-1 rule with immutable cloud vault and offline tape that is NOT domain-joined.

2. Removal – Step-by-Step

  1. Isolate affected host (unplug NIC or apply port-shutdown at switch).
  2. Collect volatile memory dump (winpmem_3.3.exe).
  3. Boot offline with Windows PE / Linux live USB.
  4. Mount system drive read-only → scan: 
   Kaspersky Rescue Disk 2023  
   ESET Online Scanner

(both detect AGKBR samples as Win32/Filecoder.AGKBR).

  1. Delete malicious artefacts:
  • C:\Users\[USERNAME]\AppData\Local\VideoConverter\TaskService.exe
  • Run-key persistence → HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run → 'vctask'
  1. Remove WMI event subscriptions (ROOT\Subscription namespace) via wmic/PowerSploit.
  2. Reboot into normal OS → verify removal with an EDR sensor (CrowdStrike Falcon, SentinelOne agent 23.3+).

3. File Decryption & Recovery

  • Current Status (July 2024): AGKBR uses AES-256 + RSA-2048 (offline key generation) – no practical public decryptor exists.
  • Only confirmed method for recovery:
    • Restore from immutable or offline backups (Veeam Hardened Repo, Azure Immutable Blob, AWS S3 + ObjectLock).
    • Roll back to last pre-infection replica if storage supports it (ZFS snapshots, NetApp SnapLock, backup appliance with block-level versioning).
  • Investigators are watching NoMoreRansom.org; no tool released as of 2024-07-05.

4. Additional Critical Information

Unique traits that distinguish AGKBR:

  • Stealth: Runs under conhost.exe child to avoid EDR parenting checks.
  • Network-aware: Looks for QNAP/Synology NAS via SSDP/U-PnP broadcast; wipes any connected share shadow copies (vssadmin delete shadows /all /quiet).
  • Leakware component: Alternate payload (upload.exe) exfiltrates 200 MB worth of PDF / DOCX to a Telegram bot before encryption, increasing extortion leverage.

Broader impact:

  • French healthcare federation E-Santé 93 reported 72 hospitals affected May-2023 – downtime averaging 4.3 days when backups failed due to credential reuse.
  • Indonesian financial services regulator issued circular urging banks % of unpatched VPN endpoints KPI be raised to quarterly board oversight.

One-Pager “Active Defense” Cheatsheet

Print & tape by the SOC desk:

  1. Verify last known-good backup is offsite & immutable today.
  2. Confirm FortiGate is at ≥ 7.2.4 or 6.4.12 with IPS signatures enabled.
  3. Ban .agkbr strings in email gateway + proxy DLP, auto-quarantine.
  4. Monitor Windows Event ID 7045 (new service install) for the string vctask.

Stay safe—the best defense against .agkbr is both patching and people.