Office (OOXML) / .XLSX malware analysis — malicious · 590635a0f8af5a0f

MALICIOUS

Office (OOXML) / .XLSX

1.41 MB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000

MD5: 15a11e563f7a3a496e30d5cf6bec79d9 SHA-1: 75fee8b70763140576a48ecccd0fae95475d025f SHA-256: 590635a0f8af5a0fb018d8b3420d7325c59bdcfea65111f60689a9e1fcabb10b

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1559.001 Component Object Model Hijacking

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. The embedded object, 'xl/embeddings/i8kIhlO.m6t', likely contains the exploit code and the initial stage of the malicious payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/i8kIhlO.m6t 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` `415c06efb6d25f659b50c9d3f90e5e861c8fb190a0ea54e61d42f32077cbd60b`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/i8kIhlO.m6t	1728000 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` `51a224814cf64a7685efe453c334e2e9ddc47a1c70c6d8b30be127aa8051a4ae`	ole-package	OOXML xl/embeddings/i8kIhlO.m6t Ole10Native stream: ole10nATIvE	1711940 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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