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

Static analysis result for SHA-256 99feae8ef0422c9b…

MALICIOUS

Office (OLE) / .XLSX

1.19 MB
MD5: 76eaa01acb9f26a9ff73d4c42ea74b65 SHA-1: a2ccb3205a034368a7f79262a8305e45d8975f9c SHA-256: 99feae8ef0422c9b36b0031102e05d65b6d5028987b5fd421a8ce4e206ac2863
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.002 Phishing: Spearphishing Attachment

The sample is an OOXML file that is encrypted with a default password and contains an Equation Editor OLE object. This object carries a payload-like Ole10Native stream, indicating it's likely an exploit carrier. The presence of the Equation Editor OLE object strongly suggests exploitation of a vulnerability within it for initial execution.

Heuristics 4

  • 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.
  • 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.
  • Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY
    Default-encrypted OOXML embedded OLE object declares the Equation Editor CLSID but stores a large high-entropy Ole10Native stream with malformed package sizing. This is exploit-shaped Equation/OLE payload evidence.
  • 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.