Office (OOXML) / .XLSX malware analysis — malicious · 8cfeb4d76cb22a9b

MALICIOUS

Office (OOXML) / .XLSX

1.62 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-04-29

MD5: 3909326959d5d5db11039408b0bcc1bd SHA-1: 8e4abe31e9b0eee9cc12db6788e5c86c9f586806 SHA-256: 8cfeb4d76cb22a9b1736afcfb1fd9cfe08e55bb1143560a343989aa7620f0e40

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious File T1559 Component Object Model Hijacking

The sample is an Office Open XML (OOXML) XLSX file containing an embedded OLE object, specifically a Microsoft Equation Editor object. Heuristics indicate this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded artifacts, 'ooxml_oleobject_00.bin' and 'ooxml_oleobject_00_ole10native_00.bin', are likely components of the exploit or the delivered payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/02PNu.q5wWUwB 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` `fe21d2d05db7e48310b28076c70ed64f0bf28712d37d528e966110912bcdb80f`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/02PNu.q5wWUwB	2001920 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.98, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `2daccca4fc7e805a5f2b19217b5dd2103402955050b1d1b26f34930e5701c235`	ole-package	OOXML xl/embeddings/02PNu.q5wWUwB Ole10Native stream: oLE10NATiVE	1983857 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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