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

Static analysis result for SHA-256 efcfc634c5c7f22e…

MALICIOUS

Office (OOXML) / .XLSX

735.3 KB Created: 2023-09-04 22:03:29 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2023-09-05
MD5: c18dfea43882d5559a2bd2dc6f159832 SHA-1: 8172f17ec8048a8cb0bee79591612f0a92be4a9c SHA-256: efcfc634c5c7f22eb1e2631e5c9b95812e218b8e949f7d49060c237ce1ce6050
100 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 Malicious File

The XLSX file contains an embedded OLE object, specifically identified as a Equation Editor object. This object exhibits an anomaly where the Ole10Native stream appears to carry a payload, indicated by an impossible header and a significant discrepancy between declared and actual stream sizes. This strongly suggests the exploitation of a known Equation Editor vulnerability (CVE-2017-11882) to execute arbitrary code, likely leading to the download and execution of a secondary malicious payload.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/TeDAUJCT3.bDDEkM 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
0bf5e9a91ccb0ef9db4dad7fecf635e467732a603f608fa5a0ea65f2c061432b		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/TeDAUJCT3.bDDEkM 1046528 bytes
ooxml_oleobject_00_ole10native_00.bin
17327702aa67de473c5af9ddaa7bbe070d36d6e519c40987fed06353c9b91b5b		 ole-package OOXML xl/embeddings/TeDAUJCT3.bDDEkM Ole10Native stream: OlE10nATiVe 1035893 bytes

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