Office (OOXML) / .XLSX malware analysis — malicious · 5f5caa58b605a3a0

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: f0e45bac527285564bb7559bbe98e5a5 SHA-1: 9ac440981491e2b278ee7cd723cc895d0daf3891 SHA-256: 5f5caa58b605a3a0f3b84250fce5ed3a408d3b27f4f5f844c2a5865f018c7029

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The file is an Excel document containing an embedded OLE object, specifically identified as an Equation Editor object. Heuristics indicate this object exhibits anomalies consistent with CVE-2018-0798, suggesting it's designed to exploit a vulnerability for client-side execution. The embedded object's Ole10Native stream has high entropy and a declared size significantly larger than its stream size, indicating a potential payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/R7vkOErFG.yBtuo 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` `9e789f35b1da3631ddb399893297f156f6e6108b20deb07325d9a42cf8a5e6b0`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/R7vkOErFG.yBtuo	2300928 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` `ed376dddec7f61afd0f6f4651323b1b9785cddc7869a166924eed85d7b285846`	ole-package	OOXML xl/embeddings/R7vkOErFG.yBtuo Ole10Native stream: Ole10Native	2280062 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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