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

Static analysis result for SHA-256 fce384c48c432c8a…

MALICIOUS

Office (OOXML) / .XLSX

2.91 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2025-10-29
MD5: 9e1ae6c6f1731643e9eb707faf1a54ab SHA-1: 844c693fbc14f9c1628ebaffa4b631bb75e548ad SHA-256: fce384c48c432c8ad209f2094757ed53738a6b1734b7b1d4aeafc5bb0ab2483b
140 Risk Score

Malware Insights

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

The sample is an Office Open XML (OOXML) file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object carries a payload-like stream with an anomalous header and a significant size discrepancy, strongly suggesting exploitation of a known vulnerability like CVE-2017-11882. The presence of a NOP sled further supports the likelihood of shellcode execution.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/9Mi.k7CES contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • NOP sled detected high SC_NOP_SLED
    Found 20+ consecutive 0x90 bytes
  • 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
3afb6431cf1afaea045af128399272c90375162ce404bf9b52f2df2cee7d1ab3		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/9Mi.k7CES 3011584 bytes
ooxml_oleobject_00_ole10native_00.bin
0bfb91b4e1ef373c90b77cedef038ea636aeb9ddcd64a960d720336b054271f0		 ole-package OOXML xl/embeddings/9Mi.k7CES Ole10Native stream: oLE10nAtivE 2985880 bytes

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