Office (OOXML) / .XLSX malware analysis — malicious · 4bc046f4ece9e9cd

MALICIOUS

Office (OOXML) / .XLSX

829.1 KB Created: 2021-08-09 02:12:21 UTC Authoring application: Microsoft Excel 12.0000

MD5: a0d55e0a1d28e681680a6a88700a06fe SHA-1: 23337f670eba5d9c50efe44742b49ab472e78f98 SHA-256: 4bc046f4ece9e9cd78d4f9bfb9fc49e3bd458f7d0dee608cb73be6468341c137

140 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an Excel file containing an embedded OLE object, specifically an Equation Editor object. High-severity heuristics indicate that this Equation Editor object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. This technique is commonly used to deliver second-stage malware. No document body or scripts were extracted, but the presence of the malicious Equation Editor object is sufficient evidence for this assessment.

Heuristics 4

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/Mu.svcziT 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` `f24f3bee72a360bc2b1cf42d7a401dc4718856839e068ce5b934709c90151d4e`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/Mu.svcziT	1138688 bytes
`ooxml_oleobject_00_ole10native_00.bin` `b3e899a29495353d8378e8a0ac374aec7cfd2e7b7962f2d960303414e3a87f9a`	ole-package	OOXML xl/embeddings/Mu.svcziT Ole10Native stream: OLe10NaTive	1126989 bytes

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