Office (OOXML) / .XLSX malware analysis — malicious · 39fe9e87b9c5b0dc

MALICIOUS

Office (OOXML) / .XLSX

1.34 MB Created: 2022-11-18 02:05:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: 25dc349369d0035c5ed1fff3cd896e76 SHA-1: 2e13297d2f2700b265c71d01d2cd4b8c92c7544b SHA-256: 39fe9e87b9c5b0dc38342083c826c1b4b41905e827b426c103f021e87c73d02e

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1559.001 Component Object Model and Distributed Component Object Model

The file is an Excel spreadsheet containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristic analysis indicates this object is anomalous and likely carries a payload, exploiting CVE-2018-0798. The embedded artifact exhibits high entropy, consistent with a packed or encrypted second-stage payload. No document body or scripts were extracted, but the presence of the vulnerable Equation Editor component strongly suggests an exploitation attempt.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/dLrFNblj.jfS 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` `83dcbe64e872bf544da0b36d749695e57eeab20582ff008fe9c58e3e31dbb538`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/dLrFNblj.jfS	1638912 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` `859be407c67a7f0df2f45881bd3ee9b1121f6cc146315c10fc684f522c9803c1`	ole-package	OOXML xl/embeddings/dLrFNblj.jfS Ole10Native stream: OLe10NAtIVe	1623998 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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