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

Static analysis result for SHA-256 ff77f81a1967eeaf…

MALICIOUS

Office (OLE) / .XLSX

1.17 MB
MD5: 6f37460eb47e7065e28d56cd83833b58 SHA-1: 2e0a883429f4a397026338e49936fc7c3cd9b8b2 SHA-256: ff77f81a1967eeaf198f4a05923f8a2c4305959124387e78bf60ba7e1db31231
200 Risk Score

Malware Insights

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

The file is an encrypted OOXML document, identified as malicious by ClamAV. High-severity heuristics indicate the presence of an Equation Editor OLE object that carries a payload-like stream, suggesting it's designed to exploit vulnerabilities. The encrypted nature and the specific OLE object strongly point towards a downloader or exploit carrier.

Heuristics 5

  • 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.
  • ClamAV: Xls.Downloader.af2fa5c5d0587870-9978799-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.af2fa5c5d0587870-9978799-0
  • 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.
  • Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY
    Default-encrypted OOXML embedded OLE object declares the Equation Editor CLSID but stores a large high-entropy Ole10Native stream with malformed package sizing. This is exploit-shaped Equation/OLE payload evidence.
  • 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.