Office (OOXML) / .XLSX malware analysis — malicious · 81ef9d7d493dd6f2

MALICIOUS

Office (OOXML) / .XLSX

744.7 KB Created: 2023-08-03 11:34:29 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-08-04

MD5: 7bcf4664357c2c884e814ccd6e894018 SHA-1: 09e34a6970af08e364d97c861f0d1b3954eb4280 SHA-256: 81ef9d7d493dd6f2706e21851567557974abafd54a5c25292c3d742223c96af0

100 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an Excel 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 size, strongly suggesting exploitation of a known vulnerability (e.g., CVE-2017-11882) to execute arbitrary code. The embedded object's path and stream name are logged as IOCs.

Heuristics 3

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/cC.kXzS05d 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.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `25e32b09e6b995cc9f4fef29236bec7571d1c4c80aec9fded9eeeb00a62a8006`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/cC.kXzS05d	1093632 bytes
`ooxml_oleobject_00_ole10native_00.bin` `9c9572ca598fad7f0c441c8d4b74dc9e4ed42fcb3e8c3e447bcf26a4df66a732`	ole-package	OOXML xl/embeddings/cC.kXzS05d Ole10Native stream: Ole10NAtiVe	1082404 bytes

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