Office (OOXML) / .XLSX malware analysis — malicious · 8b1e232161ec8681

MALICIOUS

Office (OOXML) / .XLSX

2.31 MB Created: 2023-08-03 11:34:29 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-08-17

MD5: 5639b635abfd1000986d3c9fd74cc20b SHA-1: b4e13583d3bb0956e7d3ec799481dbf8ebdc78b4 SHA-256: 8b1e232161ec868173117a79b7c5e2394bda26741220eeff23597a0cda01fc0a

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1559.001 Component Object Model Hijacking

The file is an Excel spreadsheet containing an embedded OLE object, specifically a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object is anomalous and likely carries a malicious payload, exploiting CVE-2018-0798. The embedded object's native stream exhibits characteristics of a second-stage payload, suggesting the Excel file is a delivery mechanism for further malicious activity.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/j2K.XG 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` `a58ba3e89d2adbb46e6355f764ba9f9ab26f4d6b09d25fdb9ba4272c8ac39d48`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/j2K.XG	2744320 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.97, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `d46c5fa0d9e591b508b1f1815e88f0665290eef12a797164a06866a408f2f659`	ole-package	OOXML xl/embeddings/j2K.XG Ole10Native stream: OlE10nATIVe	2720755 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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