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

Static analysis result for SHA-256 f637bd1f5fd0c0c1…

MALICIOUS

Office (OLE) / .XLSX

350.4 KB
MD5: 63614e4c1f7c86c41ade29b98f006f64 SHA-1: 42fbc34e108d77b4f1856bb5f29dc6e5aef2fce5 SHA-256: f637bd1f5fd0c0c1fc12d69a95ff12582dcbe6ba0b09e25fb085598f9dcdb3ab
180 Risk Score

Malware Insights

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

The sample is a password-encrypted Excel spreadsheet. Heuristics indicate it contains an embedded Equation Editor OLE object, a common carrier for exploits. The encryption and malformed CFB FAT suggest an attempt to hinder analysis and potentially conceal malicious content. The primary attack vector is likely a spearphishing attachment leveraging an Equation Editor vulnerability.

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.
  • 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.