Office (OOXML) / .XLSX malware analysis — malicious · 3df521e9d317f61a

MALICIOUS

Office (OOXML) / .XLSX

135.4 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000

MD5: ee5237ced437943e28804114a89fd5ab SHA-1: 98346a31eac37ee0782cfc3867a49a86e6968826 SHA-256: 3df521e9d317f61aa62f5156f18ef03ecee2dad470665ba4932719275af87071

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1027 Obfuscated Files or Information

The sample is an Office Open XML (XLSX) file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded OLE object and its associated native stream are the primary indicators of malicious activity, likely leading to the execution of a secondary payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/oleObject1.bin 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` `c86331da84dfab548efd536487e8faf71d3d3c1f40a05379692e4fe1e488ffef`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject1.bin	133632 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.97, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `e4281e5772708143f0bc2e4cd3b6a9f4ef383a7af842aeff22dd98b9f54a72bc`	ole-package	OOXML xl/embeddings/oleObject1.bin Ole10Native stream: olE10NatiVe	129751 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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