Office (OOXML) / .XLSX malware analysis — malicious · 2efb5ead574a05af

MALICIOUS

Office (OOXML) / .XLSX

4.10 MB Created: 2021-03-23 07:05:13 UTC Authoring application: Microsoft Excel 12.0000

MD5: d2c23008ba724369c4b137b392f31fa0 SHA-1: 958bedd1172301d07a350ef6a6a11ee5065aba85 SHA-256: 2efb5ead574a05afddfd8148a425aea1b11509701ce05fa1c500eb3b67f82d80

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1559.001 Component Object Model Hijacking

The sample is an Excel file containing an embedded OLE object, specifically an Equation Editor object. Heuristics indicate this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798 or a similar Equation Editor vulnerability. The high entropy and size of the Ole10Native stream within the OLE object point to a packed or encrypted second-stage payload being delivered.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/LbB.3HxYoz 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` `c8b9a92abcbd2529e442536a6799bdcc3fd12d401fa4e24514501054924f68ea`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/LbB.3HxYoz	4622848 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` `a521f84c7608ece3838644c6f168c9c3d677db13a58194cc6941c313a5f5b0a5`	ole-package	OOXML xl/embeddings/LbB.3HxYoz Ole10Native stream: Ole10Native	4584061 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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