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

Static analysis result for SHA-256 c72431033202a9e4…

MALICIOUS

Office (OLE) / .XLSX

1.26 MB
MD5: 36185ec0950db83f2f8fc9543481cd3e SHA-1: c4e5b55f2a0da2cc02d9aafd7890dc4c31438643 SHA-256: c72431033202a9e4c4ad3428082a85d98ebab24d21e4a54dafeef9be4cafbc94
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an encrypted OOXML file that contains an Equation Editor OLE object. This object appears to be a carrier for a malicious payload, indicated by the OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY heuristic. The encryption with a default password and the presence of the Equation Editor exploit suggest a common delivery mechanism for exploiting vulnerabilities in older Office versions. No scripts were extracted from this sample.

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.