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

Static analysis result for SHA-256 1d8d30236d903d69…

MALICIOUS

Office (OLE) / .XLSX

575.1 KB
MD5: 0fc97b349c3a7e1c0dee2d70613c734e SHA-1: 8c78aefd118e936fc809855df79e811ea3bd3c9d SHA-256: 1d8d30236d903d69d06701681ff9dd0ce2d587cce5d99f0c856a77312c67cc66
140 Risk Score

Malware Insights

MITRE ATT&CK
T1553.004 Subvert Trust Controls: Mark-of-the-Web Bypass

The sample is a password-encrypted OOXML file identified as an exploit carrier. The encryption and malformed structure suggest an attempt to evade static analysis and potentially bypass security controls. The specific encryption method and malformed nature point towards a malicious intent, likely to deliver a secondary payload upon successful decryption or exploitation.

Heuristics 4

  • 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.
  • 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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