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

Static analysis result for SHA-256 c1fd79b84966afe2…

MALICIOUS

Office (OOXML) / .XLSX

489.1 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: a19dd2e7c1ee829e96e26dfc855f3355 SHA-1: 1ff45d8f1ec50640b8aa1fce81f0c63383048339 SHA-256: c1fd79b84966afe2cc160baa76ae7f57d0206efe373bedd4cf5c9691c3ca203f
108 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

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 presence of hidden sheets further supports the concealment of malicious activity. No scripts were extracted, and the embedded object's nature points towards a direct exploit rather than a downloader.

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
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
6f2fb51e7b31546d55079570558e56762852a33d1eef94c043f51d5a539edcef		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 4096 bytes
ooxml_oleobject_00_ole10native_00.bin
7b8063d3d72f24f98ff26126d97d40f59ea49269c9cfa7ed3d3e22d4dd4eb3f1		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: oLe10nATIVe 1525 bytes
emf_00.emf
d16ad4543cd2b4f8c4b40aef4b7d6ab7567f19b9648b725b3c79fd4c20221a1f		 ooxml-emf OOXML EMF part: xl/media/image6.emf 653280 bytes

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