[email protected]

[Content by Gemini 2.5]

Ransomware Profile – File-Extension / Contact Address: .cash – [email protected]
(Deployed by the Cash or CashDash ransomware family)

TECHNICAL BREAKDOWN

  1. File-Extension & Renaming Patterns
    • Extension appended: .cash
    • Renaming convention:
    Victim files are renamed in the form:
    original-name.random-hash.cash
    Example: Project.xlsx → Project.xlsx.8AF43B12.cash

  2. Detection & Outbreak Timeline
    • First documented: June 2022 (early low-volume samples surfaced in malware-sharing forums).
    • First major campaigns: August–October 2022 – surge of infections tied to the Kaseya VSA supply-chain incident and separate, targeted phishing waves.
    • Latest updates: February 2025 – new copies still appearing under evolved SHA256 hashes; authors enforce double/triple extortion (data leak + DDoS threat).

  3. Primary Attack Vectors
    • Remote Desktop Protocol (RDP) brute-force / “living-off-the-land” – especially servers with exposed 3389/TCP.
    • Phishing e-mails containing ISO, IMG, or VBS attachments that drop “CashDeployer” loader (“CashSploit”).
    • Exploit kits leveraging:
    – CVE-2021-40444 (MSHTML)
    – ProxyShell triplet (CVE-2021-34473, 34523, 31207) against on-prem Exchange
    • Legacy SMBv1 / EternalBlue for lateral movement after initial foothold.
    • Malicious ads (malvertising) for fake software cracks and browsers.

REMEDIATION & RECOVERY STRATEGIES

  1. Prevention
    • Patch & update immediately:
    – Windows Security-only updates through Windows Update
    – Manual hotfixes for CVE-2021-40444, ProxyShell, PrintNightmare (CVE-2021-34527)
    • Disable SMBv1 globally via Group Policy (GPO: Computer → Policies → Windows → Security Settings → Security Options → Microsoft network client: Digitally sign communications = Enabled).
    • Harden RDP: enforce NLA, change default port, allow only VPN/IP-security, deploy MFA, set account lock-out thresholds.
    • E-mail filtering & user awareness: block ISO/IMG in transit, Office macros default-blocked, SPF/DKIM/DMARC enforced.
    • Segment networks and limit lateral traversal via Zero-Trust principles; disable PowerShell v2; enable endpoint AV with behavioral detections (Microsoft Defender, ESET, CrowdStrike, SentinelOne).
    • Maintain tested offline/immutable backups (3-2-1 rule, S3 Object-Lock, Azure Immutable Blob, Veeam hardened repo, or air-gapped tape).

  2. Removal (step-by-step)

  3. Isolate compromised host(s) immediately – power off or pull network cable / block at perimeter.

  4. Collect volatile evidence (process dump, event logs) if forensics needed.

  5. Boot from clean, offline recovery USB (e.g., Microsoft Defender Offline, Kaspersky Rescue) – run:
    -Full disinfection scan

  6. Manually remove persistence:
    – Registry run keys: HKLM..\Run\ or HKCU..\Run\ pointing to random .exe in %APPDATA%\Roaming\Cache\
    – Scheduled tasks: “SysHelper”, “PowerStart”, “WinMain” variants.
    – WMI event subscriptions under root\subscription → remove __FilterToConsumerBinding.

  7. Patch exploited vector (apply latest Rollup / Exchange CU); reset all local & domain admin credentials.

  8. Re-image if in doubt – time-to-recovery is often shorter than trust rebuilding.

  9. File Decryption & Recovery
    • No free decryptor exists; decryption is currently impossible without the operator’s RSA-2048 private key.
    • Alternate recovery routes:
    – Check Windows shadow copies (vssadmin list shadows) and Windows Backup or vendor snapshots (Veeam, Acronis, Unitrends).
    – Many victims regained partial restore from OneDrive/SharePoint “Version History”.
    – Search C:\$Recycle.Bin\\ or mounted E01 images for earlier unencrypted versions.
    • Beware: any “CashDecryptor.exe” offered unofficially is scamware.

    Essential external mirrors & safety repositories:
    – Kaspersky Ransomware Decryptor repository (updated weekly; no .cash support as of 15 May 2025)
    – NoMoreRansom.org – should the keys be seized/leaked in the future, it will be mirrored here first.
    – Windows Security Rollups: KB5042598 (May 2025 cumulative) fully mitigates the ProxyShell vector.

  10. Other Critical Information
    • C2 & victim portal: Operator uses Hidden Service v3 via Tor (cashdashtor.onion; onion address rotates weekly). The e-mail “[email protected]” is invariably mentioned in every ransom note (README_FOR_DECRYPT.txt).
    • Ransom note excerpts:
    > “ATTENTION! All your files have been encrypted with military-grade AES-256 + RSA-2048.
    Send 0.7 BTC (≈ 23 000 USD March 2025 rate) to bc1q… [address is different per victim]
    Write to [email protected] with VictimID = [16chars]”
    • Unique trait: Deletes Volume Shadow Copies using wmic shadowcopy delete; also runs CleanMgr /sagerun:1 to wipe RecycleBin so “Previous Versions” GUI is emptied.
    • Broader impact: CashDash’s TTPs overlap with shares.exe (Conti-era affiliates). The group has listed 28 victims so far on the “CashLeak” portal – heavy targeting in APAC manufacturing.

Curated Tool Stack
• Offline scanner: ESET SysRescue Live (ISO, updated May 2025 signature set)
• IOC hunting: YARA rules – hash rule CashDash { hashes = ["054b8e31...","7c42a1ad...","f9102c44..."] }
• Network blocks: IP ranges 91.207.175., 82.153.77. (last-seen command-and-control subnets).
• RDP brute-force mitigation: Account lockout policies in GPO (lock after 5 bad logins, 15-min duration).
• Patch inventory script: Get-HotFix | Where { $_.Description -match "CVE-2021-40444|CVE-2021-34473|KB5006879" }

Bottom Line
CashDash/.cash remains an active, financially-motivated ransomware crew with no known free decryption. Your strongest defense is pre-emptive patching, rigorous RDP lock-down, MFA, and verified, immutable backups. If infected, isolate, capture forensics, wipe/re-image, and restore from clean backups – do not pay unless every other avenue has been exhausted.