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

Static analysis result for SHA-256 ceef223bf6dc75ff…

MALICIOUS

Office (OLE) / .XLSX

1.22 MB
MD5: 79cbe5c736dca5564640e51892f32c1b SHA-1: dca92a17d05be974c19ddea73ced3786d0eebe0f SHA-256: ceef223bf6dc75ffe9eb1af19d6d440b59def1fa06230ca79511eae1c155d37a
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 embedded Equation Editor OLE object. This object is known to be used as a carrier for exploits, and the anomaly detected in the Ole10Native stream suggests it contains a malicious payload. The high entropy of the stream further supports this. The file is likely delivered as an attachment, leading to the exploitation of the Equation Editor vulnerability.

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.