Office (OOXML) / .XLSX malware analysis — malicious · b6a9ac14a6f86310

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: eed3176f73f4cad98183f4420a9766e7 SHA-1: cd13795cfb85f8284f634ca7fbba90d862c661ed SHA-256: b6a9ac14a6f863101cfc6c1821a82e21ccd63d9cc6cffedd382612efc1793881

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.001 Malicious Link

The file is an Excel spreadsheet containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object carries a payload and exploits CVE-2018-0798 due to anomalous native stream properties. This strongly suggests the file is designed to exploit this vulnerability for initial execution of a secondary payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/ceU9pI.5hweBk 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` `162770c3e3416fa1a76f504a634c38353fb28c5ef6a107fd0625c2debc7811d0`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/ceU9pI.5hweBk	1807360 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` `323242c0be68923018dfa913aa9db7ed35d69e81346b2fe238650227bcd48174`	ole-package	OOXML xl/embeddings/ceU9pI.5hweBk Ole10Native stream: Ole10Native	1790533 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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