Office (OOXML) / .XLSX malware analysis — malicious · a750c8558d270b26

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: edeb11bbfa3b5033f634142d2a5e6a92 SHA-1: 34e6f4aac9dc9a00b8efd20b18b8a85c2754f596 SHA-256: a750c8558d270b26c9b49db7221a062bfb0b60162a9f16f80dcafeecf99b0f2b

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.001 Malicious Link

The sample is an Excel document 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 is high-entropy and appears to be a second-stage 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/XYuT.7HNY7rE 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` `d40eee6d8ce325c680cbd84c62c2a6287ee0cd8f1473c48c613d001a4b3d0ffd`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/XYuT.7HNY7rE	1428480 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `244b9a227e3842e298141d8e1bcce0936c544a014ffb89e182d4752909cf8220`	ole-package	OOXML xl/embeddings/XYuT.7HNY7rE Ole10Native stream: Ole10Native	1414848 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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