Office (OOXML) / .XLSX malware analysis — malicious · 21621f9116f4ee2a

MALICIOUS

Office (OOXML) / .XLSX

2.26 MB Created: 2023-08-03 11:34:29 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-08-10

MD5: c13c5925a8a0c7f63af33c38c4a815de SHA-1: 0f75f21666d6bcce9583076c597c934342cab45c SHA-256: 21621f9116f4ee2a958d59b8af1981cecbba7ca9b799f0d4489f103401ae20b3

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 vulnerable Equation Editor object. Heuristics indicate that this object carries a payload-like Ole10Native stream, exploiting CVE-2018-0798. This suggests the file is designed to deliver a second-stage payload via exploitation of the Equation Editor vulnerability.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/wmmd.BJ 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` `8e025a3a7da3492307f97538d16824c42fbb74459bd1a51f284d78255d50013f`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/wmmd.BJ	2649088 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` `bb58c3d61d3b9addab1b226b1691343f9e984805182bda4045c3aa3080da86f9`	ole-package	OOXML xl/embeddings/wmmd.BJ Ole10Native stream: oLE10natIVe	2625746 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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