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

Static analysis result for SHA-256 455f67e6c660ee9e…

MALICIOUS

Office (OLE) / .XLSX

229.5 KB
MD5: cf2abe5fe68fecd99df4ceb9337ce525 SHA-1: 90785d16ac0796ce2872b6242456fd2a01082799 SHA-256: 455f67e6c660ee9e3f733a39790fa57e81c56ca17b4f720aa3c02e2cdfb784fb
280 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is a password-encrypted XLSX file identified as malicious by ClamAV. High-severity heuristics indicate it uses an Equation Editor OLE object (xl/embeddings/oleObject1.bin) to exploit CVE-2018-0798. The encryption and malformed structure suggest it's designed to evade static analysis and deliver a secondary payload. The specific exploit and encryption method point towards a sophisticated attack.

Heuristics 7

  • 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.
  • ClamAV: Win.Malware.Agent-9914332-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Malware.Agent-9914332-0
  • 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.
  • 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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