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

Static analysis result for SHA-256 fcde7b2708053160…

MALICIOUS

Office (OLE) / .XLSX

1.24 MB
MD5: 4a044c98d5e93a64d63e0bd2aa4f14d8 SHA-1: b4207e5d063863a06d094d51862c4f2ade6f2604 SHA-256: fcde7b2708053160d0d4b6347faa1963bd0bc15006a77e65f168a8ae0a31bccd
140 Risk Score

Malware Insights

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

The sample is an encrypted OOXML file that contains an Equation Editor OLE object. This object is known to be used as an exploit carrier, often delivering a second-stage payload. The presence of the 'OLE_EQUATION_EDITOR' and 'OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY' heuristics strongly suggests exploitation of a vulnerability within the Equation Editor. The default password encryption further indicates a deliberate attempt to obfuscate the malicious content.

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.