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

Static analysis result for SHA-256 af7e8839f5b44d1a…

MALICIOUS

Office (OOXML) / .XLSX

2.05 MB Created: 2025-06-12 01:12:31 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2025-06-28
MD5: f4119afdd43295cc0a695ac423420f2a SHA-1: 04890b83c75912c640872021c273ea4d6c95611a SHA-256: af7e8839f5b44d1a0d59d102046ab33534172857aa6de4cfb9a7045931170c2c
100 Risk Score

Malware Insights

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

The sample is an Office Open XML spreadsheet 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, suggesting it is being used to exploit a known vulnerability for arbitrary code execution. The presence of this embedded malicious object strongly points to a delivery mechanism for a secondary exploit or payload.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/RC.if 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
4a23aa309f911553b8e22d66e6453970f29fb98b524e57737721a5bc108c4847		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/RC.if 2905600 bytes
ooxml_oleobject_00_ole10native_00.bin
be90d20e09469f0ca5a530087e7cdf0962c7cbab84a18c770459117c0efc3d07		 ole-package OOXML xl/embeddings/RC.if Ole10Native stream: oLE10natIvE 2880469 bytes

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