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

Static analysis result for SHA-256 f3c3c0c49c037e7e…

MALICIOUS

Office (OLE) / .XLSX

569.0 KB
MD5: 5edbd82c98bab74dd3583540299fd6af SHA-1: 881fcb634d3bcf43699e8e8f132653f050086fe0 SHA-256: f3c3c0c49c037e7efa2fbef61995c1dc97cfe2887281ba4b687bdd6aa0a44e0a
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1059 Command and Scripting Interpreter

The sample is an encrypted Office spreadsheet that contains an embedded OLE object, specifically an Equation Editor object. Heuristics indicate this object is malformed and exploits CVE-2018-0798, a vulnerability in Equation Editor. This suggests the document is designed to exploit this vulnerability to execute a malicious payload. No document body or scripts were extracted, limiting further analysis of the payload's specific actions.

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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