Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 005db2e014ce6758…

MALICIOUS

Office (OLE) / .XLSX

187.1 KB
MD5: 97bcd631b42c3830367a1d3f141142d5 SHA-1: d482b2c6fa457b982d936fe0c2ccd7bda5ed30bd SHA-256: 005db2e014ce6758d8fb08ddc8d9efbf34ededd092bc6e955a8131d96b7d5e22
240 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1566.001 Phishing: Spearphishing Attachment T1204.002 Malicious File Execution: Malicious Code

The file is an encrypted Office document, identified by ClamAV as Doc.Downloader.Formbook. The presence of an Equation Editor OLE object and embedded macro-enabled documents strongly suggests it's a carrier for malicious code. The encryption and malformed structure indicate an attempt to evade static analysis, likely to download and execute a secondary payload.

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.