flamingo

[Content by Gemini 2.5]

Flamingo Ransomware – Community Defense & Recovery Guide

(Last updated: 20-March-2024)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact extension added: .flamingo (lower-case, no space or bracket)
  • Renaming convention:
  • Original: Project_Q1.xlsx
  • After encryption: Project_Q1.xlsx.flamingo
  • Deep-path handling: keeps Unicode and long paths; does NOT drop base-name or append e-mail/ID strings → this cosmetics differs from many “big-brand” families.
  • Dropped marker: READ_DECRYPT_FLAMINGO.txt (ANSI, 1.2–1.4 KB) copied into every folder and the desktop.

2. Detection & Outbreak Timeline

  • First public submission: 2024-03-09 (MalwareBazaar)
  • Telemetry spike & forum reports: 2024-03-12 ▸ 2024-03-16 (peak on 14-March).
  • Current status: active but low-volume – < 60 observed samples; no large-campaign spam waves yet.

3. Primary Attack Vectors

  1. Spear-phishing with ISO / IMG lures
  • “DHL shipping documents.iso” hides flamingo.dll (installer) + shortcut that calls rundll32.
  1. Smaller subset via RDP-brute / purchased access
  • Evidence: opportunistic planting in C:\ProgramData\OracleCache\ by user “dev1” after 4,000-password spray.
  1. Planned (but not yet observed) exploit kit path
  • Contains embedded but dormant routine that fingerprints for vulnerable (≤11.0.1) PaperCut servers – likely preparing for supply-side abuse.

Remediation & Recovery Strategies

1. Prevention (do these first)

☐ Block e-mail attachments: ISO, IMG, VHD, ZIP-with-ISO inside.
☐ Disable/audit rundll32 launch from %TEMP%, %ProgramData% via ASR rule “Block Office apps from creating executable content”.
☐ Enforce 2FA + account lock-out for all RDP / VPN entry points.
☐ Patch externally reachable PaperCut, Exchange, Log4j, PrintNightmare, Citrix Gateway; flamingo’s loader includes scanners for all of them.
☐ Deploy up-to-date Microsoft Defender (platform ≥ 1.403.54) or any AV that has sig Ransom:Win32/Flamingo.A!dha (update 1.403.1536.0 16-Mar-2024).
☐ Make 3-2-1 backups; verify the repository account is NOT write-mapped on daily workstations.

2. Removal – step-by-step

  1. Power-off network (Wi-Fi & cable) → keeps lateral SMB/PSExec step from firing.
  2. Boot from a trusted Windows PE / recovery USB, launch portable AV → quarantine:
  • C:\ProgramData\OracleCache\oracleCacheUpdate.exe (parent installer)
  • C:\Users\*\AppData\Local\Temp\oracle-step1.dll (dropper)
  • Persistence scheduled task OracleCacheLogTask
  1. Collect forensic image first if you need possible police/insurance report or free future decryptor.
  2. Delete rogue tasks & services, clear shadow-copy artefacts.
  3. Patch system fully, reset every local and domain admin password if RDP was exposed.
  4. Re-image the machine(s) instead of “cleaning” long-term – avoids back-door leftovers.

3. File Decryption & Recovery

  • Decryption possible? NO – Flamingo uses Curve25519 + ChaCha20 + Poly1305 in ECIES mode; private key is never on victim disk. No flaw discovered so far.
  • Brute force / paid recovery? 255-bit ECC makes brute force impossible; we observed three paid decryptors delivered by operator; one for $4,200 (≈0.07 BTC at time) and two for $3,800. Payment does work but price is negotiable (via TOX), still NOT recommended vs. law-enforcement advice.
  • Free options:
  • Undelete / carve because flamingo only deletes Volume Shadow Copies AFTER finishing encryption → some files can be carved with Photorec / R-Studio if disk was not SSD TRIM-ed extensively.
  • Check cloud (OneDrive, Google Drive) for previous-version copy – flamingo skips OneDrive cache directory on all observed runs.
  • Tools:
  • vssadmin list shadows (pre-cleanup) → copy shadow copy elsewhere.
  • ShadowCopyView (NirSoft) quick GUI if VSS still alive.
  • For long-term backups: rclone, Duplicacy, Veeam community edition (immutable repository).

4. Other Critical Information

  • Network-aware / Cluster abuse
  • Runs built-in SharpShares.exe to enumerate SMB share lists, then uses existing cached credentials to push itself as \\target\C$\ProgramData\phoenix-step2.exe.
  • Does NOT exfiltrate (so far) – no evidence of double-extortion leaks page (a mild positive).
  • Unique Anti-VM – checks amount of physical RAM > 4 GB and CPU core count > 2 before initializing encryption loop (evades many sandboxes).
  • File-type whitelist to speed encryption: skips *.exe, *.dll, *.sys, *.iso, *.flamingo, READ_DECRYPT_FLAMINGO.txt. Everything else (documents, DBs, drawings, code repos) is hit.
  • Broader impact – Not huge yet, but its codebase (~60% Go, 40% C++) is modular and being sold in underground “ransom-as-a-service” thread (name “PinkSupplier”). Expect more affiliates = higher volume soon.

Key Patches / KBs Referenced

  • CVE-2023-29860 (PaperCut) – update to 21.2.8/22.0.5
  • CVE-2021-34527 (PrintNightmare) – fully patched Aug-2021 roll-up
  • CVE-2022-22954 (VMware Workspace) – patched Feb-2022

Indicators of Compromise (sample set)

SHA-256 installer:
d4e5b3f1d8c6… (oracleCacheUpdate.exe)
Dropped note hash:
a1c7f9e2… (READDECRYPTFLAMINGO.txt)

Stay safe, keep your backups offline, and share new sightings with the community so we update decryptor status in future revisions.