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

Static analysis result for SHA-256 f8c1326f46665a68…

MALICIOUS

Office (OOXML) / .XLSX

2.84 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2025-10-01
MD5: 35b15c0e269789ae47a8ddb88343fdda SHA-1: 845bb4e3ce344bc0cad136f692d157a57bbc4473 SHA-256: f8c1326f46665a68586d8db9dc6bda7540796108a301d698238825b1a8034eb2
100 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1203 Exploitation for Client Execution

The sample is an Office Open XML (OOXML) file 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 header, strongly suggesting exploitation of a known vulnerability (e.g., CVE-2017-11882) for arbitrary code execution. The embedded object is the primary indicator of malicious intent.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/ab.LH 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
b311eff3eb61758ba88243973bff3f89ef06a11ac4d942097f348c638f197286		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/ab.LH 2881536 bytes
ooxml_oleobject_00_ole10native_00.bin
ba060fd2c61e05a77139e849819b161b2177f1467b831c999f64aec68883d82f		 ole-package OOXML xl/embeddings/ab.LH Ole10Native stream: OLe10NAtIVe 2856674 bytes

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