Office (OOXML) / .XLSX malware analysis — malicious · d546a3a7f171eb47

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 5a0a62c0b8da5d0af6812689db4dca70 SHA-1: 228b01b65966a279a720b0848082bf18590c0cec SHA-256: d546a3a7f171eb4715212359fb71bb01f3c4cdf367894ae88c67a4b0d39643f8

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an Excel file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate anomalies within the Equation Editor's native stream, strongly suggesting exploitation of CVE-2018-0798. This vulnerability is known to be used for delivering malicious payloads. The embedded artifacts, ooxml_oleobject_00.bin and ooxml_oleobject_00_ole10native_00.bin, are likely components of this exploit.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/rWA.Ljpm 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` `cd600a22ab84e53ce304128d5d5fe3d65ac20b8e6667466d4792a2d68d32caa3`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/rWA.Ljpm	1451008 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` `5bf6b81bb25006701252da5cf0a2fddd68efa80255f85b13a3d0808a324ed5f1`	ole-package	OOXML xl/embeddings/rWA.Ljpm Ole10Native stream: oLE10NaTIVE	1436908 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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