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

Static analysis result for SHA-256 f66ec7a880f49749…

MALICIOUS

Office (OOXML) / .XLSX

2.94 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2025-09-25
MD5: 0592b2a9a7fb7faf4c9f52be5fbfa582 SHA-1: 2a8cc753caf1df734beb8b2e03d16f23697be161 SHA-256: f66ec7a880f497499f9b0455a6e472a9d2360b1ceafc11d26d82ffc3bc47997a
100 Risk Score

Malware Insights

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

The file is an Excel spreadsheet 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 header, strongly suggesting it's used to exploit a vulnerability. 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/iyI.z6I0C7 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
2abfeaf8b7df7e7dac4cb0f5539e20c7f89a9b85ca053115d2dc81c432099b9a		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/iyI.z6I0C7 3005440 bytes
ooxml_oleobject_00_ole10native_00.bin
fc4a79041c0efcc616b18e0689090d92f5dc1f6e4107b7a6d7291ebf014bcbbf		 ole-package OOXML xl/embeddings/iyI.z6I0C7 Ole10Native stream: OlE10naTIVE 2979800 bytes

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