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

Static analysis result for SHA-256 7cb3ffa44654db62…

MALICIOUS

Office (OLE) / .XLSX

1.23 MB
MD5: 7c5f2178cbddc544639af018ee27181b SHA-1: b587c5fe244c025ea92e8ec1e112da5a1d151084 SHA-256: 7cb3ffa44654db626e5eaec3cf679ac8c4c033db7103fff7da4e8ccb4aacf797
140 Risk Score

Malware Insights

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

The sample is an encrypted OOXML file containing an Equation Editor OLE object. This object exhibits anomalies indicative of a payload, specifically an impossible Ole10Native header within the Equation object. This strongly suggests the file is designed to exploit a vulnerability in the Equation Editor to achieve arbitrary code 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.