Office (OOXML) / .XLSX malware analysis — malicious · fa338e3fb0614733

MALICIOUS

Office (OOXML) / .XLSX

1.25 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-07-27

MD5: a013867137d2e082e9120194402c8fd6 SHA-1: 84d588bc2fcac1635f1a25d53b6435776262caf2 SHA-256: fa338e3fb0614733050ef5ec75c25fcfebd45ab50ccaf68d36bd975a862049b7

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1559.001 Component Object Model

The file contains an embedded OLE object, specifically an Equation Editor object, which exhibits anomalies indicative of CVE-2018-0798. This suggests the file is designed to exploit this vulnerability for client-side execution, likely to download and run a secondary payload. The high entropy and size of the Ole10Native stream within the Equation Editor object further support this conclusion.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/Rfi.yeHmrpU 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` `ca96847f1b419cbb805966f54c45d851571343f81655d4651946a1843424b07f`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/Rfi.yeHmrpU	1602048 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` `26aa731c0596dab73738a224e8b54eefbd251bf058bb056088ffc4e110a1c9c7`	ole-package	OOXML xl/embeddings/Rfi.yeHmrpU Ole10Native stream: olE10nAtIVe	1586752 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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