Office (OOXML) / .XLSX malware analysis — malicious · 713d2fb35408b717

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 1461a8052c816e751955ff7a38fb5182 SHA-1: e7793c175d0b2ee297d80866edce3f44bf489a7c SHA-256: 713d2fb35408b717e4296a3c3dea7b50be79b45393f01a17a039bc93232b6b22

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an Excel spreadsheet containing an embedded OLE object, specifically identified as a vulnerable Equation Editor object. Heuristics indicate anomalies in the native stream consistent with CVE-2018-0798, suggesting it's designed to exploit this vulnerability for client-side execution. The embedded object likely contains and delivers a secondary payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/IrzdL97Y.Mctj7 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` `51f5d0c292cf9a61303b7398b44cf050421d2cb7e5f7886798284426d99d946e`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/IrzdL97Y.Mctj7	1985024 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.98, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `772835cd83c63a9125e2db705f4a0ad5b676a362f85e058dd232a164602fb8c7`	ole-package	OOXML xl/embeddings/IrzdL97Y.Mctj7 Ole10Native stream: Ole10Native	1966781 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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