Office (OOXML) / .XLSX malware analysis — malicious · 7a5a6d15651f1da6

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 073a56cf012776f595d4a6b3fe8db7d9 SHA-1: af45c60581e83fa5397a555941881ff1348eaae8 SHA-256: 7a5a6d15651f1da626bdf3859936a578e326fe9bae889a5424fae4ec553924ec

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The file is an Excel spreadsheet containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this object is anomalous and carries a payload, strongly suggesting exploitation of a known vulnerability like CVE-2018-0798. This technique allows for arbitrary code execution on the victim's machine.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/4UW.TXoLZY 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` `c3f7a8209946ed5d70729fa6ff20390cb154a042e512ba4f4aacbe29a64de108`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/4UW.TXoLZY	1744384 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` `3f8fa891da628a85e39c45f5e927bc5b0bd54594b06b0be1cf7e1a3d5b6eace9`	ole-package	OOXML xl/embeddings/4UW.TXoLZY Ole10Native stream: Ole10Native	1728443 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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