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

Static analysis result for SHA-256 fb10cd116026ce49…

MALICIOUS

Office (OOXML) / .XLSX

2.91 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2026-02-04
MD5: 8341dd02e4ea02855d2d98eb26ac75ca SHA-1: 0e81c14a388d6f299c2e9cb747567137119b07ba SHA-256: fb10cd116026ce4912245d49d329cb1208c565734068374d7864a149f73f2992
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 Equation Editor object. High-severity heuristics indicate that this Equation Editor object carries a payload-like Ole10Native stream with an anomalous size difference, strongly suggesting exploitation of a vulnerability within the Equation Editor component. This is a common delivery mechanism for malware.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/yT1.Fb1I2W 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
1c3b76cf6ba874c84fd95b293cf5f082da41fd7cdc95b6e033e103d80810d0c2		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/yT1.Fb1I2W 3040768 bytes
ooxml_oleobject_00_ole10native_00.bin
13f3144be44b0cf441e5f2591211cb36ef3dfc5641b4ebc3468979cf83613ca4		 ole-package OOXML xl/embeddings/yT1.Fb1I2W Ole10Native stream: OlE10naTiVe 3014651 bytes

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