Office (OOXML) / .XLSX malware analysis — malicious · ec1f1f5d96fc72f6

MALICIOUS

Office (OOXML) / .XLSX

740.8 KB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-02-22

MD5: 2245818438d0cb3681f0d48ee01b858d SHA-1: e55c8cb2422e5c060c65b88777d2654ecd754a34 SHA-256: ec1f1f5d96fc72f69be2290d5b3b81ac725bebe8dcd92539d5e15af3da4ce67c

140 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1204.001 Malicious Link: Malicious Link T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model Hijacking

The sample is an Excel file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. This technique is commonly used to deliver a second-stage payload.

Heuristics 4

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/Vz8bV.IT 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` `01944dde807051e41d05cf448310bd4c0423ccba9c7ec694658206a537760980`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/Vz8bV.IT	1047552 bytes
`ooxml_oleobject_00_ole10native_00.bin` `8a0c506c0fa38a05e1091694cf4271f05127a285edf07d825dc2355008369a3f`	ole-package	OOXML xl/embeddings/Vz8bV.IT Ole10Native stream: Ole10Native	1036837 bytes

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