Office (OOXML) / .XLSX malware analysis — malicious · 21e6c412b3721df0

MALICIOUS

Office (OOXML) / .XLSX

1.22 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000

MD5: a79a52e92a8ba9c82d0743d8a7a481b8 SHA-1: f3640bbacb78c8fb93cd2de2fec812f5f9419881 SHA-256: 21e6c412b3721df0c535e9f41d43e6744e990de0ea5d3634c48cb6cd62756330

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The sample is an Excel file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate that this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded object's Ole10Native stream exhibits high entropy and a suspicious structure, consistent with a malicious payload delivery mechanism. No document body or scripts were extracted, but the presence of the vulnerable Equation Editor component is sufficient evidence for this assessment.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/E1.mcCcX 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` `d31d88ab03546ea935227cecc33d826959307081173efc86927133c334d76e68`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/E1.mcCcX	1609728 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` `866d23b4262ba5f98d0abdcc35925f001fecd1296806790b7c6439f95d6b4193`	ole-package	OOXML xl/embeddings/E1.mcCcX Ole10Native stream: Ole10Native	1594690 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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