Office (OOXML) / .XLSX malware analysis — malicious · bf3705dec2db289d

MALICIOUS

Office (OOXML) / .XLSX

1.37 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000

MD5: 06759bb5005aaeb8f07e90a0af8f3e23 SHA-1: e880c2ee79c4f8c26e7f65357162af11ceaf64ca SHA-256: bf3705dec2db289da40109be95cc98195ecbf5eda5b38962add54331954eeea8

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious File T1204.002 Malicious File: User Execution: Malicious Attachment T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model

The sample is an Office Open XML spreadsheet containing an embedded OLE object, specifically an Equation Editor object. High-severity heuristics indicate that this Equation Editor object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded artifact 'xl/embeddings/PQ.FGrYe' likely contains the exploit code and the subsequent payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/PQ.FGrYe contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY

Embedded Equation Editor OLE data contains anomalous native stream bytes consistent with a CVE-2018-0798-style Equation Editor exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like, but it does not match the exact public matrix-overflow byte signature.
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
Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `763a20f11d1d89182a01d917efa0688ce4a091602f42447d3758efb3973b0a48`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/PQ.FGrYe	1693184 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `e12a424e904d9e7394301910512697d1485b68cacb889d85c18b6c3f49fe3749`	ole-package	OOXML xl/embeddings/PQ.FGrYe Ole10Native stream: Ole10Native	1677794 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.

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