Office (OOXML) / .XLSX malware analysis — malicious · 3e9a853f721f667d

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 90324174ff8c6129c6a0bd0d708388cb SHA-1: 78736b200b092dec757901c8ca44503ab133ae72 SHA-256: 3e9a853f721f667ded0118f8849a631eb6bf38484a05f2d56db41dd5b0772dd2

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1204.001 Malicious Link: Malicious File T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model Hijacking

The sample is an Office Open XML (OOXML) XLSX file containing an embedded OLE object, specifically identified as a Microsoft 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 object, 'xl/embeddings/uxu.HdksH74', is the primary indicator of this exploit. The embedded payload within the Ole10Native stream is likely designed to execute arbitrary code upon opening the document.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/uxu.HdksH74 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` `8ac75f892eaacad78820ed7d932812ceb549f20aeda856a4bcb2e8385c7f31d0`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/uxu.HdksH74	3683328 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.95, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `cd3915b77aebf17338f1b6754f790e9e2f3822ab8e1910faf8e574ca1e0090eb`	ole-package	OOXML xl/embeddings/uxu.HdksH74 Ole10Native stream: Ole10Native	3651948 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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