Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 e854375cb78eaeec…

MALICIOUS

Office (OLE) / .XLSX

207.6 KB First seen: 2022-05-09
MD5: 38139a35b230202b14d3221da94d4ec8 SHA-1: b6a6c8b1bf11f793667549686f5672f1c049ced1 SHA-256: e854375cb78eaeecc84bef7a5789c8429814177f61e0508d4797949c4fa49b39
240 Risk Score

Malware Insights

MITRE ATT&CK
T1559.001 Component Object Model Hijacking T1204.002 Malicious File

The sample is a password-encrypted Excel file that utilizes an embedded Equation Editor OLE object, a common technique for delivering exploits. The ClamAV signature 'Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0' strongly suggests a downloader functionality, likely related to the Formbook family, though direct attribution is not possible from the provided evidence alone. The encryption and malformed structure further indicate a deliberate attempt to obfuscate malicious content.

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.