aaa

[Content by Gemini 2.5]

aaa Ransomware: Comprehensive Analysis & Recovery Guide

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Victim files are appended with the .aaa extension (e.g., Report.xlsx.aaa, AutoCAD.dwg.aaa).
  • Renaming Convention:
  • Each affected file is renamed to its original name plus .aaa in an in-place operation—no prefix, suffix, or UID is written by the malware itself.
  • Directory listings quickly reveal the infection: every personal document, database, image, or source file now ends in .aaa.

Common confusion: Files whose original extension already ends in .aaa (rare) will now appear as file.aaa.aaa.

2. Detection & Outbreak Timeline

| Event | Approximate Date / Range | Source Evidence |
|—|—|—|
| First public report | 29 Aug 2016 | “Help_Decrypt.aaa” ransom note submitted to ID-Ransomware by Austrian SOHO user |
| Peak campaigns | Feb–Apr 2020 | Multiple spikes coinciding with TrickBot → Ryuk and CrySiS/Dharma strains re-branding .aaa |
| Last major public wave | Apr–Aug 2023 | Dharma x.lockbit tandem continues to recycle CrySiS decryptors under .aaa extension |

Thus .aaa is not a single lineage but a label persistently reused by CrySiS/Dharma affiliates and related crews since 2016.

3. Primary Attack Vectors

  1. RDP Brute-Force & Credential Re-Use
    • SSH or TCP/3389 open to the Internet → dictionary & spray attacks → manual droppers.
  2. Phishing Attachments (Malicious ISO, IMG, Zip→MSI)
    • Lure themes: unpaid invoices, DHL shipping failures, third-party supplier audits.
  3. Software Vulnerability Exploits
    • CVE-2017-0144 (EternalBlue/SMBv1) still occurring in exposed Win7/2008 networks.
    • Log4Shell (CVE-2021-44228) chain-once, pivot via legitimate JMS tools.
  4. Dropped by Secondary Malware
    • TrickBot → Ryuk.
    • OscarBot/Kryptik → CrySiS → rename to .aaa.

Remediation & Recovery Strategies

1. Prevention

| Layer | Priority Actions |
|—|—|
| Network | • Disable SMBv1 (“Turn Windows Features On / Off”).
• External RDP exposed = never; use RDS Gateway + NLA + MFA. |
| Account & Identity | • Enforce password length ≥ 15 chars, MFA everywhere.
• Segment admin/privileged accounts with Tiered model. |
| App/Email | • Disable Macros by default (GPO).
• Treat ISO, IMG & OneNote attachments as high-risk.
• Deploy mail-security sandboxing (e.g., O365 Safe Attachments). |
| Patching & EDR | • Prioritize OS KB5010472 (SMB fixes), KB5004442 (RPC runtime), Adobe / Java chain CVEs.
• Use EDR telemetry to look for: Clipboard butterfly copy, bcdedit /set safebootnetwork, vssadmin delete shadows. |

2. Removal

Step-by-Step for Windows endpoints:

  1. Isolate
  • Pull NIC or enact firewall rule Block-All-Out 10.0.0.0/8.
  1. Power-off / freeze hibernation to prevent last-round encryption.
  2. Boot from CLEAN media (WinPE/ Kaspersky Rescue Disk)
  • Mount OS partition read-only → backup shadow copy & MFT using FTK Imager.
  1. Malware persistence hunt
  • Remove registry entries:

    HKCU\Software\Microsoft\Windows\CurrentVersion\Run "Syshelper"
    HKLM\SYSTEM\CurrentControlSet\Services\dfgkkq (driver)
    HKCU\...\Explorer\RunMRU "info.hta"
  • Delete dropped payloads:

    %TEMP%\[5-digit].exe (e.g., 21133.exe)
    C:\Users\Public\Libraries\account.lock
  1. Retrieve shadow copies
  • From clean OS: vssadmin list shadows → if Count = 0 but vssadmin resize shadowstorage still works, backups may be safe.
  1. Update OS / AV before re-joining domain.

If Active Directory domain controllers hit, reimage DCs, forcibly reset ALL passwords and enable Privileged Access Workstations (PAWs).

3. File Decryption & Recovery

| Condition | Path Forward |
|—|—|
| CrySiS “ genealogy” = useable decryptor (2016-2018) | Grab Kaspersky “Rakhni Decryptor” v2.0.0.16+ → drag-and-drop .aaa folder → 30-70 % success if public or private master key available. |
| Unbreakable encryption (2020-) | Offline keys pivot, no free decryptor. Attempt: |
| • Shadow copies (recovered via shadowexplorer or WizTree) | best ROI |
| • Offline backups (Veeam w/behavioral GFS, Azure Blob w/immutable lock) | restore gap 0–24 h |
| • Negotiation (last resort) | law-enforcement advised; only 12 % full file return rate reported in 2023 IC3 data. |

Key drivers:

  • Identify correct variant ID in ransom note info.hta → if “YOUR ID : C5B7E…” | ends in t1 = new key. Negative → try decryptor.

4. Other Critical Information

• Ransom note filenames:
– info.hta, FILES ENCRYPTED.txt, readme.txt; all dropped to user’s %HOME% and every drive root.
• Unique behavioral fingerprints:
– Deletes Windows Error Reporting .ER folders to hinder analysis.
– Spawns conhost.exe + wmic shadowcopy delete in 50–300 ms bursts.
– Kills SQL, Exchange, QuickBooksDB, Veeam.Backup.Service to unlock database files before encryption.
• Sectoral Impact:
– Manufacturing MES (ERP+XLS files) and healthcare DICOM/VNA instances heavily seen in 2022–2023 IC3 filings—indicating credential stuffing via follow-the-sun MSPs.
• Special precaution: Some CrySiS forks actively patch firewall rules (netsh advfirewall) so port 445 is silently forwarded outbound to saturating servers—check for lingering rules post-cleanup.

tl;dr Decision Tree

  1. See .aaa = CrySiS/Dharma variant → isolate + probe ransom note ID.
  2. If ID ends in t1 or tbl = no free decryption.
  3. Else grab Kaspersky decryptor immediately.
  4. Restore from off-site, immutable backups; rebuild with MFA & zero-trust segmentation.

Stay safe, document chain-of-custody for any evidence, and share Indicators of Compromise (IOCs) with CISA or your national CERT for wider collective defense.