Office (OOXML) / .XLSX malware analysis — malicious · 4b40782a2246d04c

MALICIOUS

Office (OOXML) / .XLSX

1.69 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-05-30

MD5: b6938df6a95765a7284fdba667cf93ab SHA-1: 9e8098939c5042a14e903b8ffbba215d06a7e1ea SHA-256: 4b40782a2246d04c2506000dce87b0dd5ea5c7819d0d5476b9c10c2067d68f43

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The file is an Excel spreadsheet containing an embedded OLE object, specifically a Microsoft Equation Editor object. Heuristics indicate this object exploits CVE-2018-0798, a vulnerability in the Equation Editor. The object contains a high-entropy Ole10Native stream, suggesting it carries a malicious payload. The embedded artifact 'xl/embeddings/Mmwo8e1l.cUTft' is identified as the likely carrier of this exploit.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/Mmwo8e1l.cUTft 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` `aa7054de92029d37ef702b574eced2e86d8e1c20bf067c76ff8c8686af913301`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/Mmwo8e1l.cUTft	2000384 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` `8afb38735ffd631837a298c2f7b8b2d6d05e6c17ae2ff7ef6710b95e9d414fe8`	ole-package	OOXML xl/embeddings/Mmwo8e1l.cUTft Ole10Native stream: Ole10Native	1981970 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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