Office (OOXML) / .XLSX malware analysis — malicious · 1b8f20adcb03d0a9

MALICIOUS

Office (OOXML) / .XLSX

1.51 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-06-27

MD5: 7dfd9b8c459aef2f70ac9c7eefb95e8c SHA-1: de77b3d074658a06cf45ebdefd4b0eb60d8ce175 SHA-256: 1b8f20adcb03d0a98eecdc184a8c7451f3f9076636d9545ae83f4572512f7b42

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious File T1559 Component Object Model Hijacking

The sample is an Excel file containing an embedded OLE object, specifically identified as a vulnerable Equation Editor component. Heuristics indicate anomalies within the Equation Editor's native stream, strongly suggesting it's being used to exploit CVE-2018-0798 or a similar vulnerability. This exploit likely delivers a second-stage payload, as indicated by the high entropy and anomalous Ole10Native stream within the Equation object.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/KyyLXj.jMXmvE 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` `5644ca85f090e4f11d558bedf8bfb28569d06868d4f4be1cb8de39d46f31cd49`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/KyyLXj.jMXmvE	1886720 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` `7615e61ed58b7e0eb011fb416cfe157745a698eea58a40c05024abe68c99ab7b`	ole-package	OOXML xl/embeddings/KyyLXj.jMXmvE Ole10Native stream: olE10nATiVe	1869619 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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