BlackCat / ALPHV Recovery
Direct answer
BlackCat (also known as ALPHV or Noberus) was the first professional ransomware written in Rust, active from 2021 until its March 2024 exit scam (Change Healthcare case, US$ 22 million). Derivative variants remain active in 2026. Uses AES with per-victim key and triple extortion (encryption + leak + DDoS). HD Doctor delivers full technical response within 6h, focused on forensics, restore and expert reports.
Do not pay ALPHV: the group executed an exit scam in March 2024 without delivering keys to paying victims. Post-ALPHV variants are even less reliable. Backup restore is the safer path.
What is BlackCat / ALPHV
BlackCat emerged in November 2021 as an evolution of DarkSide and BlackMatter. It was the first professional RaaS to use Rust (cross-platform language with small, efficient binaries). It attacked Windows, Linux and VMware ESXi with the same codebase. In March 2024, after receiving US$ 22 million from Change Healthcare (UnitedHealth subsidiary), the group executed an exit scam: shut down without distributing the take to affiliates nor delivering keys to victims. Splinters remain active.
Symptoms of BlackCat infection
- Files with random per-victim extension (e.g., .ck6up, .uoel, .anlbu, 5 to 8 chars)
- Note 'RECOVER-[ext]-FILES.txt' in each folder with Tor link
- Wallpaper changed with ALPHV/BlackCat message
- ESXi VMs powered off via /etc/init.d or mass esxcli
- AD logs with Cobalt Strike, AnyDesk, Atera (persistent access)
- Darknet site listing the company for double extortion
Most common attack vectors
| Cause | % | Recoverable? |
|---|---|---|
| Vulnerable Exchange Server (ProxyNotShell) | 22% | Patch + restore |
| VPN without MFA (Fortinet, Cisco AnyConnect) | 25% | MFA + restore |
| Exposed RDP or leaked credential | 20% | Hardening + restore |
| Targeted phishing (spear-phishing) | 15% | Training + restore |
| Vendor compromise (supply chain) | 10% | Audit + restore |
| Other / unidentified | 8% | Case-by-case analysis |
Estimated distribution from CISA AA23-061A and HD Doctor telemetry.
What NOT to do upon BlackCat identification
- 1.Do not pay: exit scam history. Original BlackCat shut down in March 2024 without delivering keys. Derivative variants have an even worse reputation. Payment is extremely high risk.
- 2.Do not reboot ESXi before snapshot. BlackCat-Linux encrypts the datastore but keeps VMs on disk. A datastore snapshot preserves data for recovery attempts.
- 3.Do not run the received decryptor without testing. Even when the group delivers a decryptor, it may contain a backdoor or be partial. Always test in isolated environment.
- 4.Do not delete the ransom note. Victim ID and public key are in the note. They are required for any decryptor attempt.
- 5.Do not disconnect SAN storage before forensics. BlackCat attacks VMware datastores via NFS/iSCSI. Disconnecting before preservation may lose critical forensic evidence.
HD Doctor process for BlackCat response
Technical response focused on ESXi (BlackCat's preferred target) and Windows Server.
- 1
Triage and containment (0 to 6h)
Segment isolation, full ESXi datastore snapshot before any action, RAM capture on hosts, vCenter and ESXi log preservation.
- 2
ESXi forensics (6 to 48h)
Analysis of /var/log/vmkernel.log, /var/log/hostd.log, identify the Rust binary (BlackCat-Linux), attack timeline via vCenter Tasks & Events, rclone-based exfiltration.
- 3
Decryptor evaluation (24h)
Match against FBI key base (Dec 2023 Bishop operation), evaluation of post-exit-scam splinter variants.
- 4
VMware restore (3 to 20 days)
Veeam restore (preferred) or VMDK reconstruction when the virtual disk header was encrypted but internal data was not. Granular SQL/Oracle DB recovery inside the VM.
- 5
ESXi hardening and report (5 to 25 days)
Specific plan: MFA on vCenter, lockdown mode, disable SSH/ESXi Shell when not in use, separate management segmentation, Windows EDR. Forensic report.
Typical SLA for BlackCat response
| Scenario | Turnaround |
|---|---|
| Initial triage and containment | 0 to 6h after contact |
| ESXi/Windows forensics | 24 to 72h |
| VMware restore via backup | 3 to 15 business days |
| Granular critical VM recovery | 10 to 25 business days |
| Final technical report | 15 to 30 business days |
- BlackCat has a high ESXi compromise rate: we prioritize datastore preservation before any action.
Affected systems
| Family | Support | Notes |
|---|---|---|
| VMware ESXi 6.0+ | ✅ Primary focus | BlackCat-Linux attacks datastores directly |
| Windows Server | ✅ Full response | AD, file servers, SQL |
| Linux servers (RHEL, Ubuntu) | ✅ Forensics + restore | PostgreSQL, NGINX |
| SAN storage (NFS/iSCSI) | ✅ Datastore forensics | Dell EMC, HPE 3PAR, Pure |
| Veeam backup | ✅ Guided restore | Detects repository tampering attempts |
Why HD Doctor for BlackCat response
- 🐱Team with real BlackCat-Linux ESXi cases, with a validated playbook for datastore preservation.
- ⚡24×7 response within 6h with direct VMware Certified Professional engineer.
- 🔍Rust binary forensics: BlackCat and splinter variant analysis via specific reverse engineering.
- 💾Granular Veeam restore + VMDK reconstruction when backup failed.
- 📋Forensic report ready for regulator within 72h and judicial use.
FAQ about BlackCat
Is there a free BlackCat/ALPHV decryptor?
Partially. The FBI published in December 2023 a decryptor for specific samples from the seized darknet site. Post-seizure and post-exit-scam (March 2024) splinter variants have no public decryptor. FBI-base matching is free and should be attempted before any payment.
Is BlackCat still active in 2026?
Original operation ended in March 2024 with exit scam against affiliates (Change Healthcare case). Splinters and former BlackCat affiliates operate derivative variants in 2026, some rebranded as RansomHub and similar. Technically the Rust binary and playbook remain similar.
Why does BlackCat focus so much on ESXi?
Efficiency: encrypting a single datastore takes down dozens or hundreds of VMs simultaneously, maximizing impact. ESXi has historically low MFA adoption on vCenter, missing EDR on the hypervisor and SSH enabled. We recommend ESXi-specific hardening as a priority control.
Should I pay BlackCat without backup?
Not recommended. Objective reasons: (1) exit scam history against paying affiliates; (2) splinter variants have functional-key delivery rate below 50%; (3) payment funds new attacks; (4) OFAC sanctions apply to some operators. Evaluate rebuild with cyber insurance and legal before any move.
How long until ESXi recovery after BlackCat?
Ideal scenario (Veeam Immutable Repository): 3 to 7 days for critical VMs. No immutable backup (backup also encrypted): 15 to 45 days for partial rebuild. No backup at all: highly application-dependent, may be unfeasible. Immutable offline backup is the most important control against BlackCat.
Under BlackCat/ALPHV attack right now?
VMware specialists. Datastore preservation within 6h.