Office (OOXML) / .XLSX malware analysis — malicious · 533ea9197b5f56cc

MALICIOUS

Office (OOXML) / .XLSX

1.71 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000

MD5: f75726844d19c528686fc2a7871fa232 SHA-1: 0f0509881a384bcb1b01ebc711a4a405dd918fb2 SHA-256: 533ea9197b5f56cc362b41c0cc8d35e2dea9df8581e608a7944f59bf9bd379c6

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious File T1204.002 Malicious File: User Execution

The file is an Excel spreadsheet containing an embedded OLE object, specifically an Equation Editor object. High-severity heuristics indicate that this object is anomalous and likely carries a payload, exploiting CVE-2018-0798. The embedded OLE object's Ole10Native stream exhibits high entropy and an invalid MTEF version, strongly suggesting it's a disguised executable or exploit code. No document body or scripts were extracted, but the OLE object's characteristics are sufficient to infer a malicious intent.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/WE9e2A.8mZFV 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` `c7dd73e05f6b1a2549b325077f87588d06b3efdd985ffb185b7f5fbb41096ea2`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/WE9e2A.8mZFV	2068480 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` `38f4dba64428df71194fb6a149406c0e8ca6f9cd83ba80ec42dc97f6e927f9be`	ole-package	OOXML xl/embeddings/WE9e2A.8mZFV Ole10Native stream: Ole10Native	2049541 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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