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

Static analysis result for SHA-256 5b57ca5a2aebf9f7…

MALICIOUS

Office (OOXML) / .XLSX

2.94 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300
MD5: b19050a28fd118af5e19fd54636363d0 SHA-1: a054b003f9528f936512c69a352deca86110f388 SHA-256: 5b57ca5a2aebf9f75e4ad91c2eed54452d18a35fd1a9197b8cb8d7c058cf7753
100 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is a malicious Excel file 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 vulnerability for client execution. The anomaly in the Ole10Native stream size further supports this finding.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/CtCtr.q3J 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
fc7d09a7e1188c18606f2f59757f6ab94fe1dd6ad6c09d7e4131b66a2ce479f7		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/CtCtr.q3J 3032576 bytes
ooxml_oleobject_00_ole10native_00.bin
463d3c2725ae1eedbee8ef78d9a384a6bc5dc0325cf716aa1951edd407896efd		 ole-package OOXML xl/embeddings/CtCtr.q3J Ole10Native stream: ole10NAtIVE 3006113 bytes

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