Office (OOXML) / .XLSX malware analysis — malicious · 1deb03a5ecbc73c8

MALICIOUS

Office (OOXML) / .XLSX

1.76 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-05-09

MD5: 955a8204970399ba3fef15b77117a61c SHA-1: 4359ddf58d70a16788c2d1be756a6ebe843d7340 SHA-256: 1deb03a5ecbc73c8d6dcbf9cf18e6c614be6b24ccd8f323f11fb97925db3b5a5

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 identified as a Microsoft Equation Editor object. High-severity heuristics indicate the presence of CVE-2018-0798, an anomaly in the Equation Editor's native stream that suggests a payload is being carried. The embedded artifact 'xl/embeddings/aR6OwR7U.XSw' is likely the exploit mechanism. The high entropy and size anomaly of the Ole10Native stream further support the presence of a malicious payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/aR6OwR7U.XSw 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` `e0deb4adbb65e40f2a89fa97fca476e69dc86c70088da23eb10ece131cc0188b`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/aR6OwR7U.XSw	2111488 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` `6e55f676d8e9a616e21c1eaaba99afc82b4a82f34cfee84276347f983014c788`	ole-package	OOXML xl/embeddings/aR6OwR7U.XSw Ole10Native stream: Ole10NAtiVe	2092315 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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