Office (OOXML) / .XLSX malware analysis — malicious · 5589be5be2c12334

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 48f58f3e3647028f9fa68bc87418b5fb SHA-1: b738645e2e867f998a29688cf8b2262da2645415 SHA-256: 5589be5be2c12334f236d08fb99cc2eb430041075814d9c2841db62018a8b028

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1204.001 Malicious Link: Malicious Link T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model Hijacking

The sample is an XLSX file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-entropy anomalies within the Ole10Native stream of this object strongly indicate the presence of a malicious payload, likely exploiting CVE-2018-0798. The embedded object itself, located at xl/embeddings/rK5.AqXw, is the primary indicator of compromise. The attack pattern involves luring the user into opening the document, which then triggers the exploit within the Equation Editor to execute the payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/rK5.AqXw 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` `e3d6f5bbb0506d905d52f033e1072e8228e68719bd74804fba2d46502306dc14`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/rK5.AqXw	1372672 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.88, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `96ca3c2953c2f3db20ec7d5220a63a8a16af1208c4bab79d470dca3449ebc60d`	ole-package	OOXML xl/embeddings/rK5.AqXw Ole10Native stream: Ole10Native	1359834 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.86, consistent with packed or encrypted content.

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