Office (OOXML) / .XLSX malware analysis — malicious · f0999846e27d7158

MALICIOUS

Office (OOXML) / .XLSX

392.8 KB Created: 2020-08-17 09:05:28 UTC Authoring application: Microsoft Excel 16.0300

MD5: c43d23e74635df1400eb432c65cdee76 SHA-1: 13a213cb5dc6c6ea63db915f7e18a639f85c04b9 SHA-256: f0999846e27d7158bd06a0c2c141c3dbfd010d3cd4a70c0edec48504539888b4

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1559.001 Component Object Model and Distributed Component Object Model

The sample is an OOXML file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded OLE object and its anomalous Ole10Native stream are the primary indicators of this exploit.

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` `f889c1743312fb68236464bbcf9ff6c3f0d1af86a01ce0b39e85934d42662a27`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject1.bin	286720 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `7e95fef88c9b774129072bef357d1934677037605f55a70cae630401a031d8d2`	ole-package	OOXML xl/embeddings/oleObject1.bin Ole10Native stream: Ole10Native	281871 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.

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