Office (OOXML) / .XLSX malware analysis — malicious · 83b4bcceb36466cc

MALICIOUS

Office (OOXML) / .XLSX

1.86 MB Created: 2022-11-18 02:05:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: 12cf74ab52ec5827362157f7d9ef2471 SHA-1: 3d58354e89036239a27dfb5fbf0aa356d93e6d88 SHA-256: 83b4bcceb36466cc1d0a04bce938821d5990f4ea338ab0e4c2fd3e19df35e501

182 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious File T1204.002 Malicious File: User Execution T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: COM Hijinking

The file is an Excel spreadsheet containing an embedded OLE object, specifically exploiting a vulnerability in the Equation Editor (CVE-2018-0798). This exploit is designed to deliver a malicious payload, indicated by anomalous native stream properties and high entropy within the embedded object. The heap-spray heuristic further suggests memory corruption techniques are being employed.

Heuristics 6

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/nm8KO.PYn 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.
Heap-spray pattern detected high SC_HEAP_SPRAY

Repeated 0x04 bytes found
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` `454ed7c2629e4e33f761ba82f4c47a2f3030603a1d481a7f8eab34c03d7c8e7e`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/nm8KO.PYn	2208256 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` `fa165d8ffb5c20a195b4f691d529c013cd50bb6dc3a445fdc14c63f7bab61d66`	ole-package	OOXML xl/embeddings/nm8KO.PYn Ole10Native stream: ole10NATiVe	2188489 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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