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

Static analysis result for SHA-256 cafec9bfe595ea63…

MALICIOUS

Office (OOXML) / .XLSX

2.16 MB Created: 2025-08-06 23:16:59 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2025-10-16
MD5: 4bd4cadcf539b806caa062d878eb86a8 SHA-1: 43b90f34fe10f2ddebc0f03225a912edf6260d0c SHA-256: cafec9bfe595ea63bd8810c8730f97ef9f44db30bd9c086238b5130e2b6af96c
100 Risk Score

Malware Insights

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

The sample is an OOXML file containing an embedded OLE object, specifically identified as an Equation Editor object. Heuristics indicate that this object carries a payload-like stream with an anomalous header and a significantly larger declared inner size than the actual stream size, suggesting obfuscation or a packed payload. The presence of an embedded OLE object, particularly an Equation Editor, is a common technique for delivering malicious content, often exploiting vulnerabilities or executing embedded scripts.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/Ouu.6agP8P 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
88c3383bb495498c55d284a627b2c3a7cf342bf644b2e34ceddbab563372be03		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/Ouu.6agP8P 2973184 bytes
ooxml_oleobject_00_ole10native_00.bin
f2d0f2b0f61a3347f02d1d61d332cbe3f868ec47082f81b1d6f0228b0e77d56b		 ole-package OOXML xl/embeddings/Ouu.6agP8P Ole10Native stream: OLE10nATIve 2947505 bytes

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