Office (OOXML) / .XLSX malware analysis — malicious · fc27f743144ea605

MALICIOUS

Office (OOXML) / .XLSX

1.47 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-03-23

MD5: 1dd6a5969f62f4d0f385e9229a123cd2 SHA-1: 400a0c8a8b4158a6effef87796d7e0ee53214f3b SHA-256: fc27f743144ea6052d1e6f8803cd46f41fc5ced7afa707f8c07e90754724c417

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious File T1204.001 Malicious File: User Execution T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model

The sample is an Excel document containing an embedded OLE object, specifically a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded artifact 'xl/embeddings/e3HVYyuld.sx' is identified as the likely carrier of this malicious payload. The attack pattern involves luring the user to open the document, triggering the Equation Editor vulnerability to execute the payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/e3HVYyuld.sx 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` `601e240663b74392c349f3d1c5b041a654a950343d4e3a9bd09751f7b5f4c588`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/e3HVYyuld.sx	1784832 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` `ae1ce86d31f7f924e930136b96fb8f1ab1d2e4a9306be4e6911161d9b5809eb1`	ole-package	OOXML xl/embeddings/e3HVYyuld.sx Ole10Native stream: oLE10naTIVe	1768401 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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