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

Static analysis result for SHA-256 c88a80b5cf8453b2…

MALICIOUS

Office (OLE) / .XLSX

1.28 MB
MD5: 39ca085ce4df97ba36a9a61666be7b3f SHA-1: 5d54768181e264b616c6597a57728e5c7fda1a1f SHA-256: c88a80b5cf8453b2d5772f5f23c45d4b68df093ed2e3c9efc37d86fa14e34880
140 Risk Score

Malware Insights

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

The file is an encrypted OOXML document that utilizes a default password, a common technique to evade initial static analysis. It contains an embedded Equation Editor OLE object, which is frequently used to deliver exploits. The presence of an 'Ole10Native' stream within the Equation Editor object, with an anomalous header and a significant size discrepancy, strongly suggests it carries a malicious payload. The specific heuristics indicate a high likelihood of an exploit being delivered via this embedded object.

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.