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

Static analysis result for SHA-256 334a1afa6526d03e…

MALICIOUS

Office (OOXML) / .XLSX

819.5 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-04-25
MD5: 9f5d9da958a143736fe42859a4888cc2 SHA-1: 641c8b4fa575a421ba0d4f94037a3e64cef1acb0 SHA-256: 334a1afa6526d03ea0fd7a052ce1a1b875c4b9e4dedccb1b3176fde586843a06
160 Risk Score

Malware Insights

MITRE ATT&CK
T1559.001 Component Object Model Hijacking

The critical ClamAV detection and high-severity heuristics indicate this XLSX file is a downloader. It contains an embedded Equation Editor OLE object with an anomalous Ole10Native stream, suggesting it's designed to deliver a secondary payload. The presence of this object and its unusual stream are strong indicators of malicious intent.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/4zY.T2qZuZ3 contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • ClamAV: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0
  • 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
95cc399cd26e8d42d83495eb16e00a4b339fefe1031592a0c5ce171d85abf029		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/4zY.T2qZuZ3 949760 bytes
ooxml_oleobject_00_ole10native_00.bin
8d1945e65cb17cb0ab889ddec5f207d0d4f6a0a215445bb1bc124a936be86498		 ole-package OOXML xl/embeddings/4zY.T2qZuZ3 Ole10Native stream: OLe10NatiVe 940012 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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