Office (OOXML) / .XLSX malware analysis — malicious · 6d544e1b25b2081b

MALICIOUS

Office (OOXML) / .XLSX

861.3 KB Created: 2023-01-19 05:24:18 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-03-03

MD5: e43e70829f350e566468a8d7b158ecca SHA-1: 57a4e905a83e715a69e107dcc63f5bf8a606f9eb SHA-256: 6d544e1b25b2081b2c9f895d5045085820ba2087bed05f20c2c59cfbc44bea02

140 Risk Score

Malware Insights

MITRE ATT&CK

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

The sample is an Excel file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate that this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded OLE object and its native stream are the primary indicators of malicious activity, likely leading to the execution of a secondary payload.

Heuristics 4

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/vaEMwo1.zXN 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `1afadb3e0f918c37f579607fbb3a2e2770be24841615890432108b8d93139d77`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/vaEMwo1.zXN	1185280 bytes
`ooxml_oleobject_00_ole10native_00.bin` `3588c166b89fcf00a62c15d924a365b424600a8ae4aeea8b2587140fc230396d`	ole-package	OOXML xl/embeddings/vaEMwo1.zXN Ole10Native stream: OLE10natIVe	1173503 bytes

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