Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 10d9dae5e6399d55…

MALICIOUS

Office (OLE) / .XLSX

162.3 KB First seen: 2022-06-28
MD5: bd4fbcd4d805a039edfb4a43b17e7fe2 SHA-1: f8ffcbd4fe69117927ed5d95a34149d2c1416ee0 SHA-256: 10d9dae5e6399d55e8e26fb59b97ea8ff2f556eb5fc16aec2d2b6f7d33e811f2
262 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution

The file is a password-encrypted Office document that exploits CVE-2017-0199 via an embedded OLE object. This exploit is known to download and execute a second-stage payload from a remote URL, which in this case is http://google.github.io@198.12.81.50/document/office.doc. ClamAV detection further confirms this is a Formbook downloader.

Heuristics 7

  • 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.
  • Encrypted Office package with CFB FAT corruption critical OLE_ENCRYPTED_AND_MALFORMED
    Encrypted-package shape co-occurs with FAT-chain corruption — the documented combined evasion form.
  • 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://google.github.io@198.12.81.50/document/office.doc

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