Office (OOXML) / .XLSX malware analysis — malicious · 6b6b31ecd7ea5184

MALICIOUS

Office (OOXML) / .XLSX

1.53 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-04-11

MD5: 98f1112c652dc47200d629579a2a8cb4 SHA-1: c5e40230102226c3d03c738d6ff61dc473aaa5f5 SHA-256: 6b6b31ecd7ea5184141cf83e6566b5345a2fbe846310569deb98952ea966a1b5

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The sample is an Excel document containing an embedded OLE object, specifically an Equation Editor object. Heuristics indicate this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. This technique allows for the execution of arbitrary code, likely to download and run a second-stage malware.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/xSNi.QRnFK 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` `f8b92dd8a488a644fd677afd9dae3a111a21c9412aa70ebe3c50610cbd9feb28`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/xSNi.QRnFK	1875968 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` `bc43775353a7ff68aed1ceca95f5e9482f81558a0260d9935b85f9bc760787b3`	ole-package	OOXML xl/embeddings/xSNi.QRnFK Ole10Native stream: Ole10Native	1859053 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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