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

Static analysis result for SHA-256 66cbb2596823d7ac…

MALICIOUS

Office (OOXML) / .XLSX

728.8 KB Created: 2022-08-10 18:51:50 UTC Authoring application: Microsoft Excel 16.0300
MD5: 726492e3ebbc6e9ac4b13b817cb39351 SHA-1: 2e7356e34a58d27639f9d11ef77fc02bc686baf4 SHA-256: 66cbb2596823d7acbaaf012ab22e5b2259e9b5ce18d35d40055617524acf2785
100 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an Excel document containing an embedded OLE object, specifically identified as an Equation Editor object. Heuristics indicate that this object carries a payload-like Ole10Native stream with an anomalous header and a significantly larger declared inner size than the actual stream size, strongly suggesting exploitation of a vulnerability like CVE-2017-11882. This technique is commonly used to execute arbitrary code, leading to further stages of malware infection.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/oy.P8K 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
2b229e95fe74eae931cf8c78675b851ef3e76b145d572173499456ef1bb8f5ed		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oy.P8K 1038336 bytes
ooxml_oleobject_00_ole10native_00.bin
fa62e6b6f5f8badcf94da386bf0e6ac489cd7f4fcc0026955bfda7862948df72		 ole-package OOXML xl/embeddings/oy.P8K Ole10Native stream: OlE10NATIVE 1027597 bytes

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