Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 9c1efd61db56d0ab…

MALICIOUS

Office (OLE) / .XLSX

82.5 KB First seen: 2022-08-18
MD5: 0253efab49bfd28496df5666d7b62363 SHA-1: a2ec0427d39f64e59012e84316e68a2f762722f5 SHA-256: 9c1efd61db56d0ab1bbd548ef9a39ba7c0cecae71d20a10815d3b0bc98d06381
202 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204.002 Malicious File T1566.001 Spearphishing Attachment

The file is an Office document encrypted with a default password, which is a common technique for obfuscating malicious content. Critical heuristics indicate the exploitation of CVE-2017-0199 via an OLE2Link object, which acts as a remote loader. This loader is configured to download a secondary payload from the URL http://jmcglone.com@198.12.89.174/invc/217.doc. ClamAV detection further confirms this as a Formbook downloader.

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 http://jmcglone.com@198.12.89.174/invc/217.doc