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

Static analysis result for SHA-256 f82bac6933d4baea…

MALICIOUS

Office (OOXML) / .XLSX

2.89 MB Created: 2025-09-10 01:57:00 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2025-11-04
MD5: 684be60e66e16eb9ba3933a3ca854093 SHA-1: 064440af811926a6ba929a68c39233b6123a9b5c SHA-256: f82bac6933d4baeabfcb1264787499127f7ece3bbd15fda8ca009fdc83b04afb
100 Risk Score

Malware Insights

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

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 Ole10Native stream with an anomalous header and size discrepancy, strongly suggesting exploitation of a known vulnerability (e.g., CVE-2017-11882). This technique is commonly used to download and execute a second-stage payload.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/5v.C5 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
76d872a57e864bd744d7335b1daea494e775a367f94d2d7381e3b67881e01076		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/5v.C5 2994688 bytes
ooxml_oleobject_00_ole10native_00.bin
e3e0c1dbb9a153719848cefdcc09834e4b9f27df88b9affcb4b816f13a88fc79		 ole-package OOXML xl/embeddings/5v.C5 Ole10Native stream: ole10NAtIvE 2969016 bytes

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