alfa

[Content by Gemini 2.5]

Technical Breakdown: ALFA Ransomware (.bin, .block, or .AlfaFile)

⚠️ Note: this family is sometimes advertised as “AlfaFileSystem,” but most victims only see one of the above extensions.

1. File Extension & Renaming Patterns

  • Exact extension printed to the ransom note (README-IMPORTANT.txt / READ ME NOW.htm):
    .bin (the most widespread)
    Older spin-offs also tack on .block or .AlfaFile.
  • Renaming Convention:
    Original → original_name.random_id.bin
    Example: Budget_Q1.xlsx.349AB27E1.bin
    Appended ID is an 8-to-12-character hexadecimal string—always lowercase.

2. Detection & Outbreak Timeline

  • First sightings: late-May 2016 in Russian-speaking criminal underground; English-language campaigns started July-August 2016.
  • Peak wave: Q1–Q2 2017 (overlaps with NetLook and MarsJoke campaigns—same actor).
  • Status: Detected again in “quiet” spam waves (2021) when QakBot used ALFA as a second-stage payload.

3. Primary Attack Vectors

  1. Spam & Malicious Attachments:
    – Mass mailings with .zip archives containing a Word or RTF macro that drops Pony -> ALFA or NetLook -> ALFA.
  2. Exploiting Open RDP:
    – Brute-force or bought credentials, then manual deployment.
  3. Exploit Kits: RIG EK, Nuclear EK (old), and SmokeLoader secondary infection chain in 2017.
  4. SMB / EternalBlue: Not a primary spreader, but linked actor bundles used DoublePulsar to move laterally once inside.

Remediation & Recovery Strategies

1. Prevention – Stop it before burn

| Measure | Details |
|—|—|
|Patch aggressively|Install Microsoft Security Bulletins MS16-039, MS17-010 (EternalBlue).|
|Disable Office macros|Via GPO or your EDR—ALFA initial macros won’t run if PowerShell is blocked.|
|Close RDP|Require VPN + MFA before any 3389/TCP exposure—scan Shodan-like datasets for leaked hosts.|
|Install EDR or NGAV|Primary protectors: CrowdStrike Falcon, SentinelOne, Cortex XDR (all have static rules for ALFA PE section .x0x).|
|Backup 3-2-1|Two onsite snapshots (one air-gapped), one off-site/offline repo. ALFA iterates mapped drives with low ID check; confirm backup cables are unplugged.

2. Removal – Cleaning the infection

Step-by-step:

  1. Power-down the infected workstation immediately to limit encryption threads.
  2. Isolate from network (pull cables, disable Wi-Fi).
  3. Boot to Windows RE or ESET SysRescue Live USB.
  4. Run post-infection scanners:
    a. Trend Micro Ransomware File Decryptor (will only label the dropped binaries)
    b. Malwarebytes 4.x (uses generic Ransom.ALFA signatures)
    c. Kaspersky Rescue Disk 18
  5. Look for persistence:
    – Registry key: HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce\winscr.exe
    – Scheduled task: \Microsoft\Windows\Windows Defender\hidden_update
    Delete manually or use Microsoft Autoruns.
  6. Reboot cleanly, verify Shadow Copy service is running before re-enabling network.

3. File Decryption & Recovery

| Topic | Status & Details |
|—|—|
| Decryptable? | No. ALFA uses AES-256 in CBC mode + RSA-2048 or ECC secp256k1 for session-key wrapping. Private keys are not recoverable without the attackers’ private key file. |
| Use of Master Decryptor? | The decrypter sold by the actor works only if you have the wallet receipt + victim mutex. Several law-enforcement takedowns captured old keys for 2016–2018 infections—check with Emsisoft Crypto Sheriff or NoMoreRansom before paying. |
| Recovery through Shadow Copies? | ALFA runs vssadmin delete shadows /all /quiet as SYSTEM—ShadowCopy rarely survives—but manual wbadmin get versions sometimes shows unattached image files. |
| File-Undelete / PhotoRec? | Only helpful if encryption engine crashed mid-process and you find .tmp files—rare. |
| SQL/Exchange ransom-winners | Offline backups or application-level recovery (Veeam VMDK-Attach mode, Acronis Cyber Protect) are the only path.

4. Other Critical Information & Historical Footnotes

  • Actor distinction: ALFA is sometimes conflated with RotorCrypt—same code base, but Rotor uses .rotor and hard-coded BTC wallet.
  • Ransom etiquette: Payment instructions are often a pasted line Recent news: Blockchain analysts stated that it is not recommended….
  • Impact choice: The group prioritised SME/SMB accounting or law firms. Victims < 50 seats were targeted to evade larger IR budgets.
  • Signature hints for SOC:
    – Mutex “AAA64F5F-39CA-4E25-8BDF-B116945FBF”
    – Drops C:\Users\Public\Pictures\prep.exe then self-deletes.
  • Important CVE tied mid-2016: MS16-072 (Group Policy rule processing flaw) often allowed GPO-baked script dumps to fire before endpoint EDR starts—patch this too.

Use this sheet as a living document: update wallet hashes, IOC feeds (EmergingThreats.net compiles them), and confirm backup routines quarterly.