Office (OOXML) / .XLSX malware analysis — malicious · 73fbb286e52bc494

MALICIOUS

Office (OOXML) / .XLSX

1.10 MB Created: 2022-11-18 02:05:27 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2023-01-12

MD5: 31b0ef590ce27c30d07d9115761f7527 SHA-1: ae82f0758b7053c02e938d4816c9952f53f6a9b9 SHA-256: 73fbb286e52bc4946ebb114bd3cbd218395079930a983e0b6248bd49a5fc9da7

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The file is an Office document containing an embedded Equation Editor OLE object. Heuristics indicate this object is anomalous and likely carries a payload, exploiting CVE-2018-0798. The embedded object's structure and high entropy suggest it is designed to execute a secondary malicious payload upon opening.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/1q.gyykkl 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` `23c0600ec27a45afdb43b2a664f6b211516622a658d4629794a493bf065d83e3`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/1q.gyykkl	1406464 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.91, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `8df76d99ca3740769a5985fdb2a0043f4dbee0cf3549af8e0bfab44900e4a6f3`	ole-package	OOXML xl/embeddings/1q.gyykkl Ole10Native stream: Ole10nATivE	1393085 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.90, consistent with packed or encrypted content.

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