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

Static analysis result for SHA-256 af661dca28c3db96…

MALICIOUS

Office (OOXML) / .XLSX

774.2 KB Created: 2021-08-09 02:12:21 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-03-22
MD5: a2000cd3bf45cf83a0193000b3a36479 SHA-1: 9d36774a4fc55088e29eb741a3f4e3c308b7eaea SHA-256: af661dca28c3db96991bfd8f5fa3f10dc77ddbab9cdc476f23d7537d0e50f1ff
140 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1204.001 Malicious File: User Execution T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model and Distributed Component Object Model

The sample is an Office document containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded OLE object and its anomalous native stream are the primary indicators of malicious intent, likely leading to the execution of a second-stage payload.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/Bx.y1KURE2 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.
  • 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
ae831851c679c423ce844acb8082764bd07ef2c710f08b820f1d54bdfcde4960		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/Bx.y1KURE2 1044992 bytes
ooxml_oleobject_00_ole10native_00.bin
42f6652dbac35d894a169e54c990fb46f3c605f989d15eb6539050bda5391421		 ole-package OOXML xl/embeddings/Bx.y1KURE2 Ole10Native stream: ole10NaTiVe 1034432 bytes

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