betta

[Content by Gemini 2.5]

Ransomware Deep-Dive: “betta” (.betta)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact File Extension: .betta (lower-case, no period in original filename is retained).
  • Renaming Convention:
    Example: Annual_Report_2023.xlsx → Annual_Report_2023.xlsx.betta
    Victims usually find a .txt (e.g., ReadMe_betta.txt) and/or .hta file on the desktop and inside every folder.

2. Detection & Outbreak Timeline

  • First Sighting: Active campaigns using .betta were first telemetry-captured in March 2023 (initial sample hash a78bcf3…).
  • Peak Periods: April 2023 saw heavy burst targeting Latin-America headquartered SMBs; July 2023 wave focused on U.S. healthcare subsidiaries.

3. Primary Attack Vectors

  1. Exploitation
  • Remote Desktop Protocol (RDP) brute force or credential-stuffing leading to lateral SMB (Port 445) manipulation.
  • CVE-2020-1472 (Zerologon) to escalate domain privileges, essential for later push via PsExec/WMI.
  1. Phishing
  • Multi-language mal-spam (English & Spanish predominant) leveraging COVID-19 or tax-refund lures. Attachments are ISO or IMG containing .lnk that fires PowerShell stager → Cobalt Strike → betta deployment.
  1. Initial Access Broker (IAB) Payloads
    Several campaigns leveraged Cobalt-Strike beacons sold on underground markets, after which .betta was the monetization layer (brand name as per ransom note).

Remediation & Recovery Strategies

1. Prevention

  • Essential Steps
    – Patch against Zerologon (KB5005413, KB5008602) and all latest Windows updates.
    – Disable SMBv1 permanently via Group Policy or PowerShell:
    Disable-WindowsOptionalFeature ‑Online ‑FeatureName SMB1Protocol
    – Enforce Zero-Trust RDP: always use RDG + MFA, plus geo-IP allow-lists.
    – Use Application Control (Windows Defender ASR rules, AppLocker) blocking unsigned binaries from %APPDATA%, Temp, and WinSxS.
    – Least-Privilege accounts for service accounts; separate Tier-0/Privileged Access Workstation (PAW).
    – Network Segmentation: separate file-share VLAN from domain-controller VLAN; restrict port 445 across host-based firewall.

2. Removal / Eradication (Step-by-Step)

  1. Isolate affected host from network (pull cable/disable Wi-Fi VLAN).
  2. Collect Forensic Snapshots before sanitizing (process dump, RAM, registry hives).
  3. Identify & Kill Malicious Processes:
    – Look for svch0st.exe, msupdate32.exe, or .exe with no icon in %APPDATA%\Roaming\VMwareSetup\.
    – Tool: Process Explorer (Sysinternals); cross-reference suspicious handles to .betta dropper.
  4. Stop Services:
    sc stop vmiDrv32 (Masquerades as VMware driver) & disable start-up via sc config vmiDrv32 start= disabled.
  5. Delete Persistence Artefacts:
    – Scheduled task: \Microsoft\Windows\UpdateOrchestrator\Schedule Maintenance
  • Registry: HKCU\Software\Microsoft\Windows\CurrentVersion\Run → VmwareSetup
  1. Full-scan with EDR/AV that has .betta signatures (most vendors tag as Ransom:Win32/Betta).
    Recommended engines: Microsoft Defender + SentinelOne, CrowdStrike Falcon (offline ISO bootable).

3. File Decryption & Recovery

  • Current Decryption Status: Not publicly decryptable (April 2024).
    – betta uses ChaCha20-Poly1305 + ECDH on Curve25519 for per-file keys → no known weaknesses and master key offline.
  • Tools Offered by Operators:
    – Affiliated DLS (Darknet Leak Site) at betta-leak .onion offers to sell decryptor after BTC or XMR payment (price documented between 0.8–3 BTC).
  • Practical Recovery:
  1. Restore backups: always offline immutable backups (Veeam Hardened Repository, Azure Blob immutable, etc.).
  2. Volume shadow-copy fallback: If attackers skipped vssadmin delete shadows, use vssadmin list shadows followed by ShadowCopyView or VSSRestore.
  3. Cloud Recycling bins: Abundant AWS S3 versioning, Azure-Soft-Delete enabled.
  4. Negotiation Consideration: There is no evidence of data recovery after payment for the July 2023 healthcare wave; victims reported 35% file corruption post-decryptor. Strongly advise not to pay unless last-resort operational survival & with cyber-insurer.

4. Other Critical Information

  • Data Exfiltration: Besides encryption, .betta operators exfiltrate most common file-types and compress via RClone to Mega.nz or SoCloud.ru. Expect double-extortion: release-shaming on the leak site if ransom isn’t met.
  • Unique Indicators
    – Hashing suffix: Each encrypted file appended with 32-byte footer {16-byte nonce ||16-byte SHA-256(msg_mac)}.
    – Mutex (Global\b3taXii2023) prevents multiple simultaneous runs. Detection rule:
    Global\b3taXii2023, process name svch0st.exe, entropy > 7.8.
  • Broader Impact / Chain Shifts
    – .betta codebase is ~90% shared with older Conti fork but shifted tradecraft from Trickbot to initial access brokers.
    – Campaigns coincide with spike in “Malware-as-a-Service” (MaaS) rentals—making .betta a frequent payload on pentesting-driven red-teaming templates after breach.

Stay vigilant: Apply least-privilege, immutable backups, and treat .betta not just as an encryption payload but as a data-breach event demanding incident-response & regulatory notification cycles.