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

Static analysis result for SHA-256 971bee35a481bf4a…

MALICIOUS

Office (OOXML) / .XLSX

2.90 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2025-10-01
MD5: b7ca3e0b1e150af30ee3562eed7d1269 SHA-1: cd64a3f740a41aea1950e2f06cca4ee7210c1dc9 SHA-256: 971bee35a481bf4a86d8856040724263b83ba374710a14912660af62fc624215
100 Risk Score

Malware Insights

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

The sample is an Office Open XML (OOXML) file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. 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 (e.g., CVE-2017-11882) to execute arbitrary code. The embedded object's filename and stream name are noted as potential IOCs.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/u8IJyE.I1M 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
1d67f5ea537a7d556576ba37ddf9b5dd6d29cad9ff4e879db764461f5a01540b		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/u8IJyE.I1M 2941952 bytes
ooxml_oleobject_00_ole10native_00.bin
5846d3bcbc1eefde279d0951e9ed3cee2ca1c8491f132f7aec9e6d741c6fe4bc		 ole-package OOXML xl/embeddings/u8IJyE.I1M Ole10Native stream: olE10NATIVE 2916780 bytes

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