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

Static analysis result for SHA-256 5c38863e2e81c741…

MALICIOUS

Office (OOXML) / .XLSX

2.86 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300
MD5: 68835d856ea07e5cec9a5f3acc6f0c57 SHA-1: 33b53826c25c75a38ba0e00b4354df0c060efec7 SHA-256: 5c38863e2e81c741eb0d3a59f326aabc41a3b118ee7adba15498af6f5c080f46
100 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample contains an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate that this object carries a payload-like Ole10Native stream with an anomalous header and size discrepancy, strongly suggesting it is used to exploit a vulnerability for client execution. The specific exploit is likely related to the Equation Editor's handling of embedded objects.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/pcGSyn.nS3YS 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
2914452336e2e4e11618788dc431c9dd094baac2decac3ed202e519f54b568c4		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/pcGSyn.nS3YS 2981888 bytes
ooxml_oleobject_00_ole10native_00.bin
c198f51dd4a4e9398c5efcab2f84e71357e538954496850fbb8ad082bb59b99d		 ole-package OOXML xl/embeddings/pcGSyn.nS3YS Ole10Native stream: OLe10NATIvE 2955921 bytes

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