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

Static analysis result for SHA-256 959a1f5fbef23f7e…

MALICIOUS

Office (OLE) / .XLSX

311.2 KB
MD5: 036fb99170815a3570a3157335e66dd8 SHA-1: af9f8c77c9aaeb50532f4edb4575be4dfb8c558d SHA-256: 959a1f5fbef23f7ed04a0f7a011ebd9f3ab823a0f25e0c3c5ec03378ec716b37
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is an encrypted Office document containing an Equation Editor OLE object, which is a known carrier for exploits. Specifically, the 'CVE_2018_0798_EQUATION_NATIVE_ANOMALY' heuristic indicates exploitation of CVE-2018-0798. The document is also flagged as 'OLE_ENCRYPTED_AND_MALFORMED', suggesting potential obfuscation or corruption related to the exploit delivery. While no scripts were extracted, the presence of the Equation Editor exploit strongly suggests the intent is to execute arbitrary code.

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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