Office (OOXML) / .XLSX malware analysis — malicious · aefbd29fa01b6796

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 3550d8c381c29cbe899f1596e873ddc0 SHA-1: 85ccf6dcf2e722a5228a1d1e81e9f4f1a0ce4a21 SHA-256: aefbd29fa01b6796341be145648ff5d0c776752cdf526865a88e70e20ae32bc2

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 file is an Excel spreadsheet containing an embedded OLE object, specifically identified as a vulnerable Equation Editor component (CVE-2018-0798). This component's native stream exhibits anomalies and high entropy, indicating it likely carries a malicious payload. The embedded artifact 'xl/embeddings/0c.Keslr0' is the primary indicator of this exploit.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/0c.Keslr0 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` `79d7c814f0e789547978817c395720f2b459d17d03b409de96542af5d2e94c44`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/0c.Keslr0	1548800 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` `14462448746798232f631f8cb2f740ffb1831c9066039073f59e47aa2bd1da51`	ole-package	OOXML xl/embeddings/0c.Keslr0 Ole10Native stream: Ole10Native	1534178 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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