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

Static analysis result for SHA-256 4975909b70555a44…

MALICIOUS

Office (OLE) / .XLSX

1.26 MB
MD5: 6efa62d808261b970ec5fbb108b9ef49 SHA-1: 90b1e50fb263d2d97e4197725079efe0da7032db SHA-256: 4975909b70555a443f8acbb22ef17f932eed445bf52148043ca4a1cc10e43264
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1566 Phishing T1059 Command and Scripting Interpreter

The file is an Excel spreadsheet that is encrypted with a default password and contains embedded OLE objects, specifically targeting the Equation Editor. This indicates it's likely an exploit carrier designed to drop a secondary payload. The presence of an Equation Editor OLE object with a payload-like Ole10Native stream strongly suggests exploitation of a known vulnerability within that component. ClamAV detection as 'Xls.Downloader' further supports this assessment.

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.

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