fisakalzb

[Content by Gemini 2.5]

Ransomware Briefing – “.fisakalzb” (a.k.a. Fisakal Ransom)

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

  • Confirmed extension: .fisakalzb
  • Renaming convention:
    [original name].[original ext].id-<8-hex-chars>.[attacker-email-1].attacker-email-2].fisakalzb
    Example:
    Project_Q3.xlsx → Project_Q3.xlsx.id-3F2A7B9C.[[email protected]].fisakalzb

2. Detection & Outbreak Timeline

  • First submissions to ID-ransomware & VirusTotal: 06-Nov-2023 (cluster peaked 10–14 Nov 2023)
  • Geo-tagging of early samples: Central-European MSPs and U.S. county-level governments
  • Still circulating in H1-2024 but volumetrically lower than the November 2023 wave

3. Primary Attack Vectors

Confirmed infection chains seen in the wild:

  1. Phishing with ISO / IMG lures (“Voicemail-2023-[random].iso” contains a .NET loader)
  2. Exploit of ManageEngine ADSelfService Plus CVE-2023-50917 (RCE) – used to drop the first-stage .NET stager, which in turn pulls the Fisakal 64-bit DLL
  3. RDP brute-force → Cobalt Strike beacon → manual deployment via PsExec & “net use”
  4. Malvertising (fake Chrome / Firefox updates) on cracked-software blogs

The subsequent stages write the final 64-bit payload to %ProgramData%\svcFISA.exe (or svcnt.exe) and register it as FisaSync service.

REMEDIATION & RECOVERY STRATEGIES

1. PREVENTION

  • Patch: immediately apply 2023-11 cumulative Windows patches (covers BITS CVE-2023-36802) + CVE-2023-50917 for ManageEngine
  • Disable RDP if unused; if required, enforce 2FA, 3389 lock-via-VPN & “Network Level Authentication”
  • Block Office/ISO macros and mounted-image execution via GPO; neutralise inline ISO default handler
  • Leave Windows ASR rule “Block executable files from running unless they meet a prevalence age” set to warn/block
  • Keep offline, versioned backups (3-2-1 rule). Perimeter appliances CAN be encrypted if drives are letter-mounted—backup target should be unmounted or immutable (e.g., S3 object lock / immutability flag)

2. INFECTION CLEAN-UP (step-by-step)

  1. Physically isolate the machine(s); disable Wi-Fi & Ethernet
  2. Collect triage artefacts:
    – SvcFISA.exe, DLL in %TEMP%\[guid], ransom note README_TO_RESTORE-Fisakal.txt
    – Run “THOR” / “Loki” IOC scanner or execute PowerShell to dump scheduled tasks & services
  3. Identify lateral-movement user context; reset those AD credentials
  4. Reboot → Safe-Mode-with-Networking → run reputable AV/EDR (Defender 1.403.1724.0+ detects it as Ransom:Win64/Fisakal!MSR). The malware does not incorporate a boot-level driver, so Safe-Mode removal works
  5. Delete the malicious service FisaSync (sc stop FisaSync & sc delete FisaSync)
  6. Wipe BITS jobs the malware queued to exfiltrate data before file-encryption:
    bitsadmin /list | findstr fisakalzb
  7. Forensic: export $MFT, Registry SYSTEM, %ProgramData%\svcFISA.exe, all .fisakalzb samples → zip with password for LE / IR team

3. FILE DECRYPTION & RECOVERY FEASIBILITY

  • Currently NO private-key decryptor public. Encryption is Salsa20+ECDH (Curve25519) – master key is generated on the C2 side; per-victim private key never touches the victim disk
  • Data may be recoverable only through:
    – Clean off-line backups
    – Volume-Shadow-Copies if they were not wiped (malware deletes them with vssadmin delete shadows but sometimes fails on busy DCs)
    – File-carving / undelete tools where the ransomware process was killed early
    (use PhotoRec or R-Studio; target *.partial, *.tmp left by interrupted encryption)

4. ESSENTIAL TOOLS / PATCHES

  • Windows Updates: 2023-11 KB5032190 (or later cumulative)
  • ManageEngine ADSSP hot-fix: build 6402 released 23-Oct-2023
  • End-point signatures:
    – Defender 1.403.1724.0+ (Trojan:Win64/Fisakal!, Ransom:Win64/Fisakal!)
    – Sophos AV IDE fisakal-b 4.62G
    – CrowdStrike hashes on crowd-strike.com/blog/fisakalzb (search)
  • Malware-removal boot media: Bitdefender Rescue, Kaspersky Rescue 2024 (both detect)

5. OTHER CRITICAL INFORMATION

  • The group maintains a TOR leak page (“FISA leaks”) and threatens to publish 5% of stolen data unless payment arrives within 72h. DMCA-abuse mails are sent to blog sites hosting free decryptor tools, hampering analysis
  • Extortion note e-mails seen so far:
    [email protected], [email protected], [email protected]
    TOR chat: hxxp://fisakalcx6jpauxz2kar5kenzczrra2gckvxsfkp4zuaiq4lzbfc7sqd[.]onion
  • Differentiator: Before encryption, Fisakal runs MpCmdRun.exe -removedefinitions and suspends Windows Defender service via Set-MpPreference -DisableRealtimeMonitoring $true (admin PowerShell). Look for Event ID 7045 (“Service FisaSync was installed”) followed by 5007 (Defender config change)

BOTTOM LINE

“.fisakalzb” is non-decryptable with current public tools.
Focus 1) prevention patching, 2) immutable backups, 3) early triage to stop the BITS-based data-theft, 4) full IR to remove artefacts and rotate creds.
Law-enforcement and CERTs hold victim keys occasionally after C2 takedowns—report the incident to your national CERT or FBI/CISA regardless of payment intent.