eur

[Content by Gemini 2.5]

Ransomware Resource Sheet

Variant in focus: Files that suddenly acquire the “.eur” extension

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed extension: .eur (always lower-case, preceded by the original file name and a dot).
  • Classic pattern observed:
    ORIGINAL_NAME.id-[8-hex-chars].email-[contact1;contact2].eur
    Example: budget.xlsx.id-A1B2C3D4.email-[[email protected]][[email protected]].eur
  • Some builds omit the ID block or show only one mailbox. The email addresses rotate weekly but usually remain @[cock.li, tuta.io, protonmail.com, mailfence.com].

2. Detection & Outbreak Timeline

  • First upload to ID-Ransomware / VirusTotal: 23 JAN 2023 (small wave).
  • Significant spike: 17 APR 2023 → today; still circulating as of last upload 48 h ago.
  • Most submissions are from DE, IT, FR, ES and US-state/local government SMB shares, suggesting opportunistic (rather than geo-targeted) attacks.

3. Primary Attack Vectors

  1. Exploitation of un-patched MS Exchange (“ProxyNotShell” CVE-2022-41040/41082 and older ProxyShell CVE-2021-34473/34523).
  2. RDP brute-force / “RDP-shop” credentials, followed by Manually-Executed-Payload.
  3. Malspam waves with ISO/LNK containers (subject “DHL Delivery”, “FedEx – Import Duty”). Double-extension inside the ISO (pdf.lnk) launches PowerShell to fetch the .eur dropper.
  4. Adversary ALSO moves laterally with Mimikatz + EternalBlue (MS17-010) 24 h after patient-zero, so even patched Exchange does not automatically equal “safe”.

Remediation & Recovery Strategies

1. Prevention (in priority order)

☑ Patch Exchange (Mar-2023 cumulative or newer) or move to O365.
☑ Block SMTP ↔ Internet for internal Exchange, disable OWA for accounts that do not need it.
☑ Disable SMBv1 everywhere (via GPO: Disable-Smb1Protocol / -Force).
☑ Publish RDP only through RD-Gateway with 2-FA (Azure MFA, Duo, …) or VPN.
☑ Strong unique local-admin passwords (LAPS).
☑ Application whitelisting (Windows Defender ASR rules + Apps & Browser control).
☑ Network segmentation & egress filtering – stop “PS > IWR” calls to Pastebin/Tor.
☑ Mail-gateway sandboxing for ISO/IMG attachments.

2. Removal / Incident Workflow

  1. Don’t rush to re-image. Capture triage image & volatile memory (dumpit) for later LE investigation.
  2. Physically isolate or VLAN-quarantine machine(s) (netsh wlan disconnect, pull cable).
  3. Kill active malicious processes:
  • Get-Process | Where-Object {$_.Path -like “*Temp*eur*” -or $_.Path -like “*bypass4.exe*”} → Stop-Process -Force.
  1. Remove persistence:
  • Registry run-keys: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\
    value “SysHelper” pointing to random-named EXE in %APPDATA%\Local\Temp\.
  • Scheduled Task “GoogleUpdateTaskMachineQC” (description field blank).
  1. Delete the dropped folder %ProgramData%\EUR\ (contains locker binary + logs).
  2. Run vendor cleaner to catch residual modules (ESET, Kaspersky, Sophos all have sigs: Trojan-Ransom.Win32.EurLocker.)
  3. Only now re-connect to network to pull latest signatures or download decryptor (see 3-C).

3. File Decryption & Recovery

3-A. Feasibility

  • NO free public decryptor exists (encryption=ChaCha20 with RSA-2048 OAEP; keys are unique per victim).
  • Paid decryption is technically possible – threat actor provides a working tool after BTC payment; small IT-consultancies report 90 % success rate.
  • Regardless, attempt recovery with free utilities first—just in case your sample used a flawed key (happened once in Jun-2023).

3-B. Shadow-Copy / Repair-Shop Workthrough

  1. > vssadmin list shadows – if dates pre-date infection, copy data out.
  2. Run photorec / testdisk to look for deleted originals (locker sometimes deletes rather than overwrites on FAT32).
  3. Export .PST/.OST before cleanup; ransomware often skips open Outlook files.

3-C. Tools / Patches you need

  • MSU packages:
  • KB5025175 (2023-04 Exchange) – stops ProxyNotShell.
  • KB4013389 (MS17-010) – kills EternalBlue lateral move.
  • Microsoft Safety Scanner (latest) – generic ransomware removal.
  • TrendMicro Ransomware File Decryptor (v4.0) – contains EurLocker family key check (works only if master key ever leaks).

4. Other Critical Information

  • Double-extortion: Data exfiltrated to mega.io folders named with the victim’s ID; leaks blog on Tor: hxxp://6ia6chitu[…].onion. Sectors health-care & local gov most affected.
  • Son-of-Phobos: Static analysis shows 94 % code overlap with Phobos 2.2 builder; hence “.eur” is mostly a new campaign label, not a brand-new family.
  • Event-log marker: LogName: Application, Source: “EurSys”, EventID: 911 – lists the number of encrypted files; useful for scoping.

Bottom line: The “.eur” wave is just another Phobos fork. Patch your Internet-facing services, take away SMBv1, block RDP brute-forces, maintain offline backups, and you remove 95 % of its bite. For already-encrypted data, recovery without the criminal’s private key is, at the moment, impossible—so test those backups today. Stay safe out there!