Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 da3f3359e2448d36…

MALICIOUS

Office (OOXML) / .XLSX

750.6 KB Created: 2021-07-23 07:52:25 UTC Authoring application: Microsoft Excel 12.0000
MD5: a4025253baa6223dd98e753812ac621c SHA-1: 01e842b2443b1acd25d6d65595c4d3f9339654d9 SHA-256: da3f3359e2448d36bdd8b0ebdf074fb608f8be4fc9d996faead58e6b6d819e67
100 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1559 Component Object Model Hijacking

The sample is an Excel file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object carries a payload-like Ole10Native stream with an anomalous header, suggesting it's designed to exploit a known vulnerability. This points to a delivery mechanism leveraging the Equation Editor's known weaknesses to execute a malicious payload.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/nvTA.aca0Vbj contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
1fe553a11ca88dd4735ca5cdbab43ae83e6ee076c0dcba84b1db91ab3f7fdd07		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/nvTA.aca0Vbj 1081856 bytes
ooxml_oleobject_00_ole10native_00.bin
ac6a520e246dbdc7e96d3ca37103a06e45f8363ddbeb9a43352bd2216858f5d0		 ole-package OOXML xl/embeddings/nvTA.aca0Vbj Ole10Native stream: olE10NATiVE 1071094 bytes

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