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

Static analysis result for SHA-256 af1a2e495c046c3b…

MALICIOUS

Office (OLE) / .XLSX

2.38 MB
MD5: 7c9bf9a7a1794e2918c3a7c88067d81b SHA-1: 2d9b4e345f4aecadc5da2424975c50a0d484a836 SHA-256: af1a2e495c046c3b0e03d321c1f20c43198e2e8c88c41ab09a91ae80c5610137
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Phishing: Spearphishing Attachment

The sample is an encrypted OOXML file that contains an Equation Editor OLE object. Heuristics indicate this object is anomalous and carries a payload, specifically triggering CVE-2018-0798. The encryption with a default password and the presence of an exploit carrier shape further suggest malicious intent. Since no document body or scripts were extractable, the exact payload and delivery mechanism beyond the exploit are unknown.

Heuristics 5

  • 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.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Default-encrypted OOXML contains embedded Equation Editor data with anomalous native stream bytes consistent with a CVE-2018-0798-style exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like.
  • 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.

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