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

Static analysis result for SHA-256 f3ae1f390f004972…

MALICIOUS

Office (OOXML) / .XLSX

2.19 MB Created: 2025-08-18 05:08:49 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2025-08-26
MD5: ac8c907c502025981008ac503b647a51 SHA-1: 51baf23ee99b7923df206a8f785168648f291a76 SHA-256: f3ae1f390f004972e602b8b070160e765520a17e6b6a291a2901d69e6d349320
100 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The file is an Office document containing an embedded OLE object, specifically identified as a Equation Editor object. Heuristics indicate that this Equation Editor object carries a payload-like Ole10Native stream with an anomalous header, suggesting exploitation of a vulnerability like CVE-2017-11882. The document body content appears to be garbled or non-standard, providing no clear user-facing lure, but the presence of the exploit object is a strong indicator of malicious intent.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/BRRWe.1UzgE5 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
4e36a7e72a95df7b70f9b449dc4e16b61be4c685a7f588bc6e7128e22b068ba1		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/BRRWe.1UzgE5 3034624 bytes
ooxml_oleobject_00_ole10native_00.bin
1be96d7d944151c8f5499ed1c13fcdecfbec799f830d2a074ae868b6314eb194		 ole-package OOXML xl/embeddings/BRRWe.1UzgE5 Ole10Native stream: OlE10NativE 3008074 bytes

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