Office (OOXML) / .XLSX malware analysis — malicious · 7f03af8f9cc110a2

MALICIOUS

Office (OOXML) / .XLSX

1.39 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-04-16

MD5: c419edcbbacadee330ee7f8a9810a0df SHA-1: df35a0089b72f1775483a72517dba5741fd410f1 SHA-256: 7f03af8f9cc110a2ff8fbe81cbb4c234a66d9525ac932cdb9748a8a72adf86eb

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious File T1204.002 Malicious File: Exploitation for Defense Evasion T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model

The sample is an Office document containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this object exploits CVE-2018-0798 via an anomalous native stream, which carries a payload. This suggests the document is designed to leverage this Equation Editor vulnerability to execute malicious code upon opening.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/7JL.ItWK 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` `bdc25fbec04ba2b2e807c2511fac7cc9a55581271d76ae92d561afdef92dba4d`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/7JL.ItWK	1783808 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` `d8c23d332741088f202eac35d04cb00a13118d5cee91715fd177eb55bdd2b72f`	ole-package	OOXML xl/embeddings/7JL.ItWK Ole10Native stream: Ole10Native	1766927 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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