Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 206200354314f7fe…

MALICIOUS

Office (OLE) / .XLSX

83.0 KB First seen: 2022-08-20
MD5: efa4f260d85cde554da491e6c84e46fb SHA-1: 0e87558e0c18c753b39d0eec24b74dc6649c6799 SHA-256: 206200354314f7fef6d251b4ae8daefd215719f0746857e6ae8a4d9465d8d524
202 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204 Malicious Link T1204.001 Malicious Link: Embedded Link T1059 Command and Scripting Interpreter T1071 Application Layer Protocol T1071.001 Application Layer Protocol: Web Protocols

The sample is an encrypted Office document that exploits CVE-2017-0199 via an embedded OLE object. This exploit is known to download and execute a remote loader. ClamAV detection identifies the payload as a Formbook variant. The embedded URL is the primary indicator for the second-stage payload.

Heuristics 6

  • OLE2Link / URL Moniker → remote loader — CVE-2017-0199 critical CVE likely CVE_2017_0199
    Document contains an embedded OLE link object whose URL Moniker points to a remote URL. When the host file is opened, Office follows the link, downloads the URL, and processes the response based on its Content-Type (HTA -> mshta.exe, RTF → Word, etc.) — the documented CVE-2017-0199 primitive. The URL extension is not a reliable filter; servers can return different payloads to Office's user agent.
  • ClamAV: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0
  • Default-encrypted OOXML exploit carrier layout high OOXML_ENCRYPTED_EXPLOIT_CARRIER_SHAPE
    Default-password encrypted OOXML package contains embedded OLE object parts and additional activation/decoy parts. This layout is common in malicious Excel exploit delivery and requires inspecting the decrypted package.
  • Office document is password-encrypted medium OFFICE_ENCRYPTED_PACKAGE
    OLE container holds MS-OFFCRYPTO encrypted package (Standard Encryption (Office 2007, AES)).
  • Office OOXML encrypted with default VelvetSweatshop password medium OFFICE_DEFAULT_PASSWORD_ENCRYPTED_OOXML
    OLE EncryptedPackage decrypts with Excel's built-in VelvetSweatshop password. Office opens this transparently, and malware uses it to hide OOXML exploit parts from scanners that only inspect the outer OLE container.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://byrl.me/E7jjJ9q

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