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

Static analysis result for SHA-256 3e527c4d9d5d35e5…

MALICIOUS

Office (OOXML) / .XLSX

742.5 KB Created: 2021-08-19 14:03:52 UTC Authoring application: Microsoft Excel 15.0300
MD5: 6e2fe9937e98dcb0a15bb7dd9d9a48aa SHA-1: 0f045f261ff5820c4161bedf7e0315de8db1cb2d SHA-256: 3e527c4d9d5d35e53ba2fc878b85c885a3f75a2fdd4f76efc407a7326219570d
100 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.001 Malicious Link

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 and a significantly larger declared inner size than the actual stream size. This strongly suggests the exploitation of a known vulnerability within the Equation Editor component to execute arbitrary code. The file's structure and the nature of the heuristics point towards a classic exploit delivery mechanism.

Heuristics 3

  • 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.
  • 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
6c3fb3ef6f2c96ab86992f99fe076c29492003b9221930adbfe0977e96e2d676		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 1069568 bytes
ooxml_oleobject_00_ole10native_00.bin
1cf7ca4aa612087ce473aa75387307a1f4af558666a2d629ec490ad123d44015		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OlE10NaTIVE 1058380 bytes

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