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

Static analysis result for SHA-256 c820b91a97b6bd07…

MALICIOUS

Office (OLE) / .XLSX

1.50 MB
MD5: fb0d2c73bfacda5ae909a6f1be81f52a SHA-1: ac38b98006efd1800687baf5f49ea9b074f690fd SHA-256: c820b91a97b6bd079f1c21e996d77461d7fb10789129fc03a8131d8a5c4bd505
140 Risk Score

Malware Insights

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

The sample is an encrypted OOXML file that contains an embedded Equation Editor OLE object. This object exhibits anomalies indicative of carrying a malicious payload, strongly suggesting exploitation of a vulnerability within the Equation Editor component. The file's structure and the specific heuristics fired point towards a classic exploit carrier designed to execute arbitrary code.

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.