Office (OOXML) / .XLSX malware analysis — malicious · e5a0ba12cf226ab0

MALICIOUS

Office (OOXML) / .XLSX

1.01 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-04-04

MD5: 2fb1868dbb9d4a12e64147b4343bb442 SHA-1: 80a9bd0eb709a3696dd806eaa9cab002a9d304d1 SHA-256: e5a0ba12cf226ab04a0d24eb1c2bc868b5390a19c412a5443accd857f4ace3cb

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1559.001 Component Object Model Hijacking

The sample is an Office Open XML spreadsheet 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 object's stream 'ole10natIVE' exhibits high entropy and a declared size significantly larger than its stream size, consistent with a packed or encrypted payload. No document body or scripts were extracted, but the presence of the vulnerable Equation Editor component is sufficient to infer the attack pattern.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/RCheJup.YvkB5y1 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` `5a1120254885bf0e108b2c9cb118312fd54dbbfa368a69893b56ed35b9695f1a`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/RCheJup.YvkB5y1	1313792 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.77, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `c304f4f84615c8561b9ed02f51c1445f50a49b0c5d491cdbe6f34c6ac6582418`	ole-package	OOXML xl/embeddings/RCheJup.YvkB5y1 Ole10Native stream: ole10natIVE	1300508 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.75, consistent with packed or encrypted content.

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