Office (OOXML) / .XLSX malware analysis — malicious · 099f39609d840cb8

MALICIOUS

Office (OOXML) / .XLSX

1.19 MB Created: 2022-03-31 04:25:31 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-07-18

MD5: cf93b8638772ed3278f594490bbdee20 SHA-1: fb14a904123d41798b379645fbde1113ced2af91 SHA-256: 099f39609d840cb815eb282110dd40dc56aaf49530c0aa7e50b3686b90c492b0

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 or a similar vulnerability in the Equation Editor to achieve code execution. The embedded artifact 'xl/embeddings/COgyUyp6e.Pup' is the likely location of the exploit payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/COgyUyp6e.Pup 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` `6d57f5dbc30d1c39cd7fe9c6b15bf72faaa4490da90684000f670c42ecfca723`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/COgyUyp6e.Pup	1530368 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` `e63f1328e3f01c5f05b60c1a0bc6e0b1b7cd43b3662e878af8ceeb5cac9afd72`	ole-package	OOXML xl/embeddings/COgyUyp6e.Pup Ole10Native stream: Ole10Native	1515624 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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