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

Static analysis result for SHA-256 f78d04abe87da3fc…

MALICIOUS

Office (OOXML) / .XLSX

2.94 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2026-02-04
MD5: de1dae54446dc90b592d17d380af541f SHA-1: ae79887e3eff89c54cf018eb0cc8074b7e3b682c SHA-256: f78d04abe87da3fcbfe7e85b9de37effac02310afabfb6272f0d17d1dcadb65c
100 Risk Score

Malware Insights

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

The sample is an Office document containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object carries a payload-like Ole10Native stream with an anomalous header, strongly suggesting it's being used to exploit a known vulnerability. The embedded OLE object and its anomalous stream are the primary indicators of malicious intent, likely leading to the execution of a secondary payload.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/RB.0ygf contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY
    Embedded OLE object declares the Equation Editor CLSID but stores a large high-entropy Ole10Native stream with malformed package sizing. This is an exploit-shaped Equation/OLE payload container seen in malicious OOXML samples. It is not assigned to a specific CVE unless the MTEF/Equation Native primitive also matches.
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
9ce7001a9ed56f972cb243b62916a984f522962e7e26745574e4ef5e905e9841		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/RB.0ygf 3022848 bytes
ooxml_oleobject_00_ole10native_00.bin
5dc25130be929af7b2b3fba07fbf46873131dd52e9c7cf2c6765ed3dbab0347b		 ole-package OOXML xl/embeddings/RB.0ygf Ole10Native stream: OlE10NaTiVe 2996705 bytes

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