Office (OOXML) / .XLSX malware analysis — malicious · 33700d5863bdece2

MALICIOUS

Office (OOXML) / .XLSX

1.22 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-05-31

MD5: b8337d5842b5d1012194b10d139cb6fd SHA-1: 1e4750afb818607dc2a089e2b77935ae3e953afc SHA-256: 33700d5863bdece28d621e669053bc6fab1b67b9c34ac236c9a1cf6f8e8222c6

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 Office Open XML (OOXML) XLSX file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate this object exploits CVE-2018-0798 due to anomalous native stream properties and high entropy, suggesting it carries a payload. The embedded OLE object and its native stream are the primary indicators of malicious activity. No scripts were extracted, and no document body was available for analysis.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/MtG8jk1.Dlkon 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` `7ed68815e92466684acf9265c4cafdf0baed400e411abce67f41376cf9e24868`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/MtG8jk1.Dlkon	1532416 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` `1dadfb20498380796d4e1d70a02b0e3601d874a5f3a7762be0ea7ca7c52dcc38`	ole-package	OOXML xl/embeddings/MtG8jk1.Dlkon Ole10Native stream: OlE10nATive	1517824 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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