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

Static analysis result for SHA-256 c128eb06a3a468c6…

MALICIOUS

Office (OOXML) / .XLSX

2.02 MB Created: 2025-06-12 01:12:31 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2025-10-10
MD5: 8347b5c6d5f3c05de1ba2e6d8682d0bb SHA-1: aeb265302abd748755f3297860c383a932fd7366 SHA-256: c128eb06a3a468c6371e2eb403705ff35b125b65831817186852e496e16acf5d
100 Risk Score

Malware Insights

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

The XLSX file contains 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 Ole10Native stream, suggesting it is designed to exploit a vulnerability. This is a common delivery mechanism for malicious documents.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/5Uzbr.ACs 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
e961d53afda963833f502e83caeaee2ce8faacb84542a8384a36b90ceb7c43ba		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/5Uzbr.ACs 2821120 bytes
ooxml_oleobject_00_ole10native_00.bin
f1c958708d9f20e0196e482f676a1403915faaab0f1eb41e5aa5f365ac5a730e		 ole-package OOXML xl/embeddings/5Uzbr.ACs Ole10Native stream: oLE10NAtivE 2796343 bytes

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