Office (OOXML) / .XLSX malware analysis — malicious · f8fb933475c5f11f

MALICIOUS

Office (OOXML) / .XLSX

1.92 MB Created: 2022-03-31 04:25:31 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-07-20

MD5: f9c73da4e73055438fe1f43a74fad343 SHA-1: b5154b8b6d1c27f6c3f375eae2c6aa05a8fb0b62 SHA-256: f8fb933475c5f11fa860dcf4369de1b8ff8e2f5947dd49fd50e2a7a4f67ad384

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The file is an Excel document containing an embedded Equation Editor OLE object. Heuristics indicate this object is anomalous and carries a high-entropy payload, strongly suggesting it exploits CVE-2018-0798 to execute arbitrary code. The embedded artifact is likely a second-stage payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/o5Rr.5n 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` `48b8b2297e47a6134d972022e54e2fe986cb3462b0dbd2049c27f764186c2161`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/o5Rr.5n	2235392 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` `911b0bd15b36b1b8d4df9ba1222946c0a7b91536f80489efc8c81a57f5f02f59`	ole-package	OOXML xl/embeddings/o5Rr.5n Ole10Native stream: Ole10nATivE	2215382 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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