Office (OOXML) / .XLSX malware analysis — malicious · 2a8bcb638d418642

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 36bdaa96373a7761a8647cfe5227cbb5 SHA-1: dbb6161b1a3f0ece592b5b8b6714d86d0322b514 SHA-256: 2a8bcb638d418642a6a043b98244ac92ad47d4e9e5ede63cc24bed115b2faa79

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.001 Malicious Link

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 Equation Editor object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. This technique is commonly used to deliver second-stage malware. No VBA macros or document body text were extracted, but the presence of the malicious Equation Editor object is sufficient evidence of an exploit attempt.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/oEsqBg.xad2 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` `ca66133bfbaf0a35d2dd647eef1965aa8fd27a2515cef70f8d8f2d1bcc0c585b`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oEsqBg.xad2	1617408 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `9b562c30852339a33c41f6cf2ecd96868820a5f25d3cf0bdfe3882af988342eb`	ole-package	OOXML xl/embeddings/oEsqBg.xad2 Ole10Native stream: Ole10Native	1602250 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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