Office (OOXML) / .XLSX malware analysis — malicious · 5c8de7c3ff4d9ad5

MALICIOUS

Office (OOXML) / .XLSX

883.2 KB Created: 2019-06-18 09:03:55 UTC Authoring application: Microsoft Excel 16.0300

MD5: 98002516881d61087dc800100a83c2d3 SHA-1: e241834db18805e6ec2922c0fab55829c6225d60 SHA-256: 5c8de7c3ff4d9ad542fe30c13e84cfe205122faefb6427cf7323298eb47ab0d3

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an Excel document containing an embedded Equation Editor OLE object. Heuristics indicate that this object is anomalous and carries a payload, specifically exploiting CVE-2018-0798. This suggests the document is designed to execute arbitrary code via the Equation Editor vulnerability, likely delivered as a spearphishing attachment.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/oleObject1.bin 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` `5503ab61d91dcc2e12a3eb1147b5964dcd74840d5deff30e8b29a73b7ba4527e`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject1.bin	743424 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `7764fb9501bf71a6f7c2ec4f486c4740b8549cd19e80bd5d177129f8ecc11ff4`	ole-package	OOXML xl/embeddings/oleObject1.bin Ole10Native stream: ole10naTIve	734764 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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