Office (OOXML) / .XLSX malware analysis — malicious · 8838d5542614d45e

MALICIOUS

Office (OOXML) / .XLSX

1.62 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-04-13

MD5: 834c838b34452659f811e000276c5cf0 SHA-1: b3f202dc848274ad5b0d34b75b1a89a57a1f91a2 SHA-256: 8838d5542614d45e9a82163699f249374c4680295ebc71a79fe65b602dfbc559

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file contains an embedded OLE object, specifically identified as a Microsoft Equation Editor object with anomalies in its Ole10Native stream. This strongly suggests exploitation of a known vulnerability (CVE-2018-0798) within the Equation Editor to achieve client-side execution. The high entropy and payload-like nature of the Ole10Native stream indicate it likely contains a secondary malicious payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/Z3idcAtq.0HDb 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` `9c91bf8b15cc750358bdc4c21f5025c9ce0db6db326dc15bd43ac8088c5b32ed`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/Z3idcAtq.0HDb	1950720 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` `180d0dba0eb85194241aecf318b1f8e2e6562b53c1ed37c406f904ce5d1a3ae5`	ole-package	OOXML xl/embeddings/Z3idcAtq.0HDb Ole10Native stream: Ole10Native	1933308 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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