Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 a121a747a06374aa…

MALICIOUS

Office (OLE) / .XLSX

191.1 KB
MD5: 3f9fec5f26049affc747c13d14bb5f80 SHA-1: 11a427670e3e0df203a5bb1406a9054c52516476 SHA-256: a121a747a06374aa1e78e93a44d6394561b95aa89928aa2002b75600e8ba5c14
240 Risk Score

Malware Insights

Formbook · confidence 95%

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

The file is a password-encrypted Excel spreadsheet, identified as a malicious downloader by ClamAV. The presence of an Equation Editor OLE object within the encrypted OOXML structure strongly suggests exploitation of a known vulnerability to deliver a secondary payload. The ClamAV detection name 'Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0' directly attributes the file to the Formbook family, known for its downloader capabilities.

Heuristics 6

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Default-encrypted OOXML embedded OLE object xl/embeddings/oleObject1.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • 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.

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