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

Static analysis result for SHA-256 b1415629db6dceeb…

MALICIOUS

Office (OLE) / .XLSX

1.25 MB
MD5: a57d7b2a91993bc4c152da018d95daee SHA-1: 9aac54966602d91b627a658b8e0bac3c08a6e317 SHA-256: b1415629db6dceeb9b1fd57ebb50c5c0f47a30e5ba5766ad4feadfd56609acfd
140 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The sample is an encrypted OOXML file that contains an embedded Equation Editor OLE object. This object is known to be used as an exploit carrier, and the anomaly detected in the Ole10Native stream suggests it contains a payload. The presence of the Equation Editor OLE object and the default encryption strongly indicates an attempt to exploit a known vulnerability 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.