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

Static analysis result for SHA-256 a267cad73f6e2ac0…

MALICIOUS

Office (OOXML) / .XLSX

2.77 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2025-10-20
MD5: 1983834553efb7039877be545c1025be SHA-1: 78247b90dacf34f770e8b6c80a6ea0c272536929 SHA-256: a267cad73f6e2ac0d9155e1cfc541630902c9491ef70b30eb5aee8ed5afa780f
100 Risk Score

Malware Insights

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

The file is an Office Open XML spreadsheet 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 size difference, strongly suggesting exploitation of a known vulnerability like CVE-2017-11882. This technique is commonly used to download and execute a second-stage payload.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/Ma9Nurm.TKCugvz 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
89ceed01a0ad18aeded744fb52f7c87255ae042b5314adc32683d87b4bdbfca0		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/Ma9Nurm.TKCugvz 2763264 bytes
ooxml_oleobject_00_ole10native_00.bin
7954f50945a98a3a8eff353cdcef274257b9e3efb2cf74158212352e28f5b681		 ole-package OOXML xl/embeddings/Ma9Nurm.TKCugvz Ole10Native stream: oLE10nATivE 2739034 bytes

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