Office (OOXML) / .XLSX malware analysis — malicious · f1c8131edd3c5a30

MALICIOUS

Office (OOXML) / .XLSX

44.0 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000

MD5: beb661cdd8b710fa0ed2ec001bc3ca58 SHA-1: f5208420964220826be4ce6c715570c6d349f068 SHA-256: f1c8131edd3c5a30be572c52d2e4c15e07968bebad0ee05c49eee8374b89fe5a

102 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1027 Obfuscated Files or Information

The sample is an Excel file containing an embedded OLE object, specifically identified as a vulnerable Equation Editor component. Heuristics indicate an anomaly consistent with CVE-2018-0798, suggesting exploitation for client execution. The embedded object's native stream exhibits high entropy and an invalid MTEF version, further supporting the exploitation vector.

Heuristics 4

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/oleObject1.bin 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.
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` `3bd8eb8e3dff021c344b1ed86594a990185b978c1902710bb4e6b2b201382035`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject1.bin	39424 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.85, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `8fe323efe3a2219094ea2d19bf318cbbbe89f2c84d8c9e4aa9bf6051a17a986b`	ole-package	OOXML xl/embeddings/oleObject1.bin Ole10Native stream: olE10naTive	36577 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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