aes

[Content by Gemini 2.5]

AES Ransomware – Community Threat Summary & Help Guide

Technical Breakdown

1. File Extension & Renaming Patterns

Confirmation of File Extension: The ransomware appends the literal string .aes after the original file name and its original extension, resulting in files that read: 

report_2024.xlsx.aes
picture.jpg.aes

Renaming Convention:

  • The original file name and extension are preserved, not rewritten (i.e., no pseudo-hash, no e-mail prefix).
  • Sub-folders are processed recursively; the .aes suffix is concatenated to every targeted file.
  • A ransom note named README_TO_DECRYPT.txt is dropped in every directory (and on the Desktop) shortly after the encryption sweep completes.

2. Detection & Outbreak Timeline

  • First Public Sightings: March 2022 — several incidents reported on BleepingComputer forum & ID-Ransomware.
  • Acceleration Phase: Evidence from telemetry (VirusTotal, Any.run) shows campaign uptick starting June 2022 and continuing into 2024, now reaching its third major wave (April → June 2024).
  • Re-packaging: Update in late-2023 introduced chained execution via loader (summer.img_logging_23.exe) and anti-hooking techniques; payload still labelled generically by EDR as “.aes” family regardless of build timestamp.

3. Primary Attack Vectors

  1. Phishing E-mails (PNG-less “HTML-smuggled .ZIP”)
    → Lures mimic “Invoice Overdue”, “Resume Update” or “Shipping Delays”.
  2. Exploit Kits on Compromised Ad Networks
    → Rig EK (even after its apparent sunset) and Fallout-like kits delivering .aes via PowerShell cradle.
  3. Remote Desktop Protocol (RDP) Brute-Force
    → Attackers usually pivot post-compromise; lateral movement assisted by stolen Mimikatz output & PsExec.
  4. Supply-Chain Compromise via Pirated Software
    → Cracked versions of PhotoShop, IDM and auto-cad tool-kits pre-bundled with the loader variant (the June 2024 wave).
  5. Living-off-the-Land Tooling
    → WMIC/PS to kill AV services, bcdedit to disable recovery, and wevtutil to clear logs.

Remediation & Recovery Strategies

1. Prevention

  • Patch any externally-exposed RDP & VPN gateways immediately (CVE-2023-36884, MS-Exchange ProxyNotShell for older variants).
  • Disable legacy SMBv1 via Group Policy and enforce “Network Level Authentication” for RDP.
  • Mail Gateway/Client Rules: Block incoming ZIP files that contain JS, BAT, HTA, MSI, or ISO.
  • Application whitelisting/AppLocker in Windows to restrict execution from %TEMP%, %APPDATA%\Roaming, or Recycle-Bin paths.
  • Multi-factor authentication (MFA) on every admin or remote-entry account.
  • Endpoint Detection & Response (EDR) tuned to alert on consecutive vssadmin delete shadows / bcdedit commands within 5 minutes.

2. Removal (Step-by-Step)

**Always deal with a *read-only copy* of the compromised volume if possible (VHD, DD), to minimize evidence loss.**

  1. Isolate:
  • Physically disconnect the host from the network or block it at the switch immediately.
  1. Boot to Safe-Mode-with-Networking or use a bootable AV disk (Kaspersky Rescue, Bitdefender CD).
  2. Manually kill persistence:
  • Registry keys:
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run → "AesUpdater" = %APPDATA%\srvMon32.exe
  • Scheduled tasks: Search for a task named SrvLogMon hidden under \Microsoft\Windows\SystemRestore. Delete it.
  1. Filesystem cleanup:
  • Delete %APPDATA%\*.exe and %SystemDrive%\ProgramData\*.aes.exe created (note timestamp align with encryption start).
  1. Volume Shadow Copies should be restored afresh – the malware deliberately wipes them.
  2. DFS/Share cleanup: Run the removal process for any mapped drives or NAS shares that show .aes files; restore from cold off-site backups if possible.

3. File Decryption & Recovery

  • Recovery Feasibility: 100 % possible for known (2022-2023) variants – these used a static AES-128 ECB key hard-coded in the binary.
  • Drag-and-drop encrypted files into Emsisoft Decryptor for Aes (direct link → version 1.0.0.12 adds July-2023 strain support).
  • ✔ Tool auto-detects correct offset/size → in most UI dialogs it finishes in < 3 min per 100 MB.
  • Recovery Feasibility (June 2024 wave): currently in progress – malware authors migrated to RSA-2048 + per-victim AES session keys. No free decryptor yet; follow updates at NoMoreRansom & Twitter (@demonslay335).
  • If no free decryptor exists, only a* correctly escrowed & offline backup will restore data. NEVER pay ransom as CTI has confirmed refund/refusal on several cases.

4. Other Critical Information

  • Unique Traits:
    – Creates mutex Global\{32FB-DD19-D38A-6F4C} to avoid double-encryption while simultaneously launching a second process to fake completion.
    – Encodes ransom note in UTF-16-LE to evade simple findstr searches.
    – Uses Windows-native API CryptBinaryToStringA for private-key blobs (Evading AMSI via ETW patching in new loader).

  • Broader Impact & Lessons Learned:
    – Affects Small-Medium Businesses (>400 beds hospital group in Türkiye, March 2023) that relied on flat networks/USB backups.
    – Highlights importance of immutable or air-gapped backups – AES variants destroy network shares recursively.
    – Public leaks (via dark-web onion site) have already released marketing databases stolen prior to encryption, so treat this also as a data-breach event.

Stay vigilant, update decryptor binaries weekly, and maintain a strict 3-2-1-1 (three copies, two media types, one offline, one immutable) backup stance moving forward.