Office (OOXML) / .XLSX malware analysis — malicious · bf3a34857860559f

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: f1a5a5f37746e18d2e1033440bc4d2dc SHA-1: 9bef6f61de12491f309ac47bc50a9649bd608bab SHA-256: bf3a34857860559f5b6ad2c8b12b3a51140b62f2d36c1ece4dd6d118677cfff7

142 Risk Score

Malware Insights

MITRE ATT&CK

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

The sample is an Office Open XML (OOXML) file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-entropy anomalies within the Equation Editor's native stream (OLE10Native) strongly indicate the presence of a malicious payload, likely exploiting CVE-2018-0798. The embedded artifacts suggest a mechanism for delivering and executing a secondary stage.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/HYz5yM.NJ36J1 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` `c7ec62cd544b8c01dc6ef3ecf2ec7b9bbdc3a2d41a8235c0fc47b8c1bbded37e`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/HYz5yM.NJ36J1	1660928 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` `4f5e9b2a2d521814b4e5fa2fdcaa03852b640b722d9e804a2f23249818efaff6`	ole-package	OOXML xl/embeddings/HYz5yM.NJ36J1 Ole10Native stream: OLE10NatIve	1645280 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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