Atlas Ransomware – Comprehensive Community Technical Brief & Recovery Playbook

Technical Breakdown:

1. File Extension & Renaming Patterns

File Extension: .atlas
(This is appended to the file after the original file extension; examples: report_x.xlsx.atlas, archive.rar.atlas).
Atlas does not modify the base file names.
Common Renaming Convention:
<original_name>.<original_extension>.atlas – keeps all characters before the final dot intact. No obfuscation of original filenames; makes manual identification fast but also fuels false positives if “resave handlers” mistake the extra .atlas as a document version.

2. Detection & Outbreak Timeline

First Public Samples: Late April 2022 (initial VirusTotal sightings 23-Apr-2022).
Major Campaign Start: 27-May-2022 when victims began posting on BleepingComputer forum & ID-Ransomware started receiving spikes (≈ 120 submissions in 24 h).
Geo-Spread: North-America & Western-Europe heaviest during first 3 weeks, then pivoted to LATAM in June 2022.

3. Primary Attack Vectors

| Vector | Technique Used | Evidence / Sample Hashes |
|—|—|—|
| Exploiting AD, RDP, & PowerShell | Brute-forced public/float RDP, credential-stuffing with Mimikatz + BloodHound to escalate across DC. | 49559e1ba6af5b4c… (PowerShell downloader); ATLAS.EXE packed with AME patcher. |
| Phishing – ISO-Side-loading | Emails with ISO attachment containing LNK masquerading as invoice, executes dllhost.exe, stages Cobalt-Strike beacon, then Atlas. | Seen with subjects Re: #[INVOICE-<User-Name>] USD 3147.90. |
| Malicious Google Ads for fake AnyDesk/Downloads | Users hit compromised advertisers clicking “Download AnyDesk” -> MSI dropper -> Atlas. | Campaign went live 12-Jun-2022. |
| Shared DLL sideloading on Valid signed apps (Team Viewer, IrfanView) | Atlas DLL (ICONCACHE.dll) dropped next to signed exe to evade AV Application Allow-listing. |

Remediation & Recovery Strategies:

1. Prevention (Proactive Measures)

Disable RDP (3389) externally or hide behind VPN + MFA. If business-critical, restrict by IP allow-list.
Decommission SMBv1 (445) and patch against Coercer / PetitPotam and PrintNightmare (Atlas sometimes lands via lateral-movement kits exploiting these).
E-mail security:
• Block .iso, .img, .vhd at gateway.
• Strip double-extensions (.exe.pdf.atlas).
Use Application Allow-Listing (e.g., Windows Defender Application Control) – Atlas DLL-sideloading fails when non-whitelisted DLLs are rejected.
Backup rigor: Follow 3-2-1 (3 copies, 2 media types, 1 offline). Encrypt backups both at rest and in transit; Atlas’s new module discovered Q3-2022 scans network shares with \\\\<IP>\\C$ for vhd/bkf and encrypts backups.
Harden LDAP: Disable NTLM for LDAP services where possible, enable Priv.Active Directory Certificates’ (ESC4) audits – Atlas has been observed dumping ADCS templates to generate rogue certs.

2. Removal (Infection Cleanup)

Step-by-step minimal downtime recipe:

Isolate + Lock-Down
a. Physically disconnect or VLAN quarantine affected machines.
b. Shut off Internet-facing laptops via your EDR “contain host” action.
Identify & Terminate Processes
• Tasklist look for Atlas.exe, svchost64.exe (fake), rundll32.exe <temp dri>\ICONCACHE.dll.
• Panda/HitManPro or Defender Offline Boot Scan verifies kill.
Delete Persistency Keys
Registry:

   HKCU\Software\Microsoft\Windows\CurrentVersion\Run\AtlasService = "%TEMP%\Atlas.exe"
   HKLM\SYSTEM\CurrentControlSet\Services\AtlasRemote

Scheduled Task:

   schtasks /delete /TN "AtlasUpd" /F

Patch Vector Doorways
• Force-change all domain/enterprise admin secrets + krbtgt twice.
• Use ADSI “riskySPNs” script to eliminate unconstrained Kerberos delegation.
Phased Re-Image
Nuke-and-pave for any machine that showed lateral movement (Atlas occasionally installs CobaltStrike remote loader in %WINDIR%\System32\spool\drivers\color). Business-critical laptops may be cleaned with layered scans but guarantee integrity.

3. File Decryption & Recovery

Feasibility: ❌ Currently no free decryptor. Atlas is based on ChaCha20 + RSA-2048 hybrid cryptosystem; private key held by adversary.
Potential Outlier: If the sample you’re hit by executed in May-2022 (v1.0), there were rare cases of RSA key reuse (e=3, tiny n)—it is possible but unlikely. Check via project-atlas-decrypter if SHA256 of sample is a3733382f... (vulnerable). Beyond July-2022 the campaign fixed the key generation bug.

Tools / Patches to Apply during recovery phase:

Kaspersky REvil/Atlas scanner (build 22.214.171.124) hashes known dropped tools to detect re-infection.
June 2022 KB5014699 (Windows) – fixes RDP clipboard hijack that Atlas can exploit to copy LSASS dumps.
Update AnyDesk >=7.0.9 to counter fake installers.

4. Other Critical Information

RaaS Differentiators:
• Dual Extortion: Atlas runs native DriveScanner that searches Office365 mailboxes (via EWS API if cached creds exist) and uploads to mega-upload pre-encryption for blackmail.
• Kill-Switch – LNK Refusal: Early versions check for desktop existence of a file named ATLAS_OFF.txt; placing it before execution aborts payload (sandbox evasion 101).
Broader Impact & Notable Incidents:
• New Mexico Legal Services (May-2022) – 210 000 files, 2 TB exfil/$400 k ransom.
• Brazilian SUS Health portal outage (June-2022) due to Atlas lateral after phish.
• MITRE ATT&CK Techniques: T1190, T1078.002, T1068, T1558 (Kerberoasting), & T1490.

For SOCs: Look for MD5 8E014A4139F0... at process inject BasicBot <BE:ShMd>—Atlas plug-in adds RSA pubkey to registry key description field (HKLM\Hardware\Description\System\AtlasPub, size 270 bytes) – a handy Yara rule:

rule atlas_ransom_pub_in_registry {
  strings:
    $rp = "-----BEGIN PUBLIC KEY-----" ascii wide
    $ak = "Atlas" ascii wide
  condition:
    uint16(0) == 0xfeff and $rp and $ak
}

Final Remarks

Atlas is a hybrid ransomware strain leaning heavily on post-incursion lateral movement rather than mass-spread worms, which makes containment once inside AD far harder. The community consensus remains one of rapid backup restoration rather than waiting for decryption, as free tooling is unlikely in the short term. Share this knowledge with your peers, especially smaller orgs still running unpatched 2016 DCs—often the weakest link Atlas picks off first.

Stay vigilant.