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

Static analysis result for SHA-256 9e29d55497d3f769…

MALICIOUS

Office (OLE) / .XLSX

192.1 KB First seen: 2022-10-10
MD5: b565e236afb8ad83e7dbae4e126a7ba4 SHA-1: 555e14bf9ab08d4b98129fc335d38ab15651ff78 SHA-256: 9e29d55497d3f769dec276e1d5889cebcf39ae49fbd9f8a3ebbf81792b146d94
220 Risk Score

Malware Insights

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

The sample is an encrypted Office XLSX file containing an Equation Editor OLE object. Heuristics indicate this object is anomalous and exploits CVE-2018-0798, a vulnerability associated with the Equation Editor. The document is encrypted with a default password, suggesting it's designed to bypass basic content inspection.

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.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Default-encrypted OOXML contains embedded Equation Editor data with anomalous native stream bytes consistent with a CVE-2018-0798-style exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like.
  • 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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