Office (OOXML) / .XLSX malware analysis — malicious · 58c71e64929ebc73

MALICIOUS

Office (OOXML) / .XLSX

4.05 MB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000

MD5: 1076bc8f384e92ea5525ad5340cdc8f3 SHA-1: 080dfe378cb844e6fef7eab179c399ae386eeeb7 SHA-256: 58c71e64929ebc73e208c5820958ac2932064e3eea0bf4885519af5f284190fb

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The file is an Excel spreadsheet containing an embedded OLE object, specifically an Equation Editor object. Heuristics indicate this object is anomalous and likely carries a payload, exploiting CVE-2018-0798. This suggests the document is designed to leverage this vulnerability to execute a malicious payload upon opening.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/RklBvMu.SwzZ1 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` `f9b65b0352b18605e853fab1c250ed3f8635369d719a25f4b8e9211751fd53de`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/RklBvMu.SwzZ1	4466176 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.93, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `572600bb8ca68cd4b4078cc0fb75c08f68c28426717b764e0f67024d7c801bbb`	ole-package	OOXML xl/embeddings/RklBvMu.SwzZ1 Ole10Native stream: ole10NATIve	4428582 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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