Office (OOXML) / .XLSX malware analysis — malicious · b266ab86f5c033f9

MALICIOUS

Office (OOXML) / .XLSX

2.06 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-08-17

MD5: e7bf0dc4dc2b2e6b87eb97c0fe8c2b67 SHA-1: 5e8d3d7feb15b177fb15a7ce395f2d08fea5b64b SHA-256: b266ab86f5c033f981943185d6373b78aa0a732b9a1da5f73c2e84a3b92dcf08

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1559.001 Component Object Model

The XLSX file contains an embedded OLE object, specifically an Equation Editor object, which exhibits anomalies indicative of exploitation for CVE-2018-0798. The Equation Editor object's Ole10Native stream appears to carry a payload, suggesting it's designed to execute malicious code upon exploitation. No document body or scripts were extracted, but the presence of the vulnerable Equation Editor object is a strong indicator of malicious intent.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/3yOxQWylf.ZK 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` `34f8ef293662102a1161fa9cc72f8454a77b4cd0878385543a4b8de681912652`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/3yOxQWylf.ZK	2377728 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.97, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `a44b5de42506aa7ed3e1f02b663f70883cfaad816129712efcd1b79105420be8`	ole-package	OOXML xl/embeddings/3yOxQWylf.ZK Ole10Native stream: OLe10naTIvE	2356475 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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