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

Static analysis result for SHA-256 0cfb52cfd8822de2…

MALICIOUS

Office (OLE) / .XLSX

310.0 KB
MD5: d1a3b07e4d8ee2b121fd4174956ad239 SHA-1: 6ebcff1fd86062f3d6db0a40129cbabb92a5fe48 SHA-256: 0cfb52cfd8822de212124339882bc5d6cbbb3ceb53a1b9a54458768afbf4f072
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an encrypted Office document containing an Equation Editor OLE object, a known carrier for exploits. The presence of 'OLE_EQUATION_EDITOR' and 'OOXML_ENCRYPTED_EXPLOIT_CARRIER_SHAPE' heuristics strongly suggests exploitation for client execution. The document's encrypted nature and the embedded OLE object point towards a spearphishing attachment delivery method.

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.