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

Static analysis result for SHA-256 f4b0d79748f50d34…

MALICIOUS

Office (OOXML) / .XLSX

958.5 KB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2021-10-11
MD5: b81e11b4bf92094131205049e2976c70 SHA-1: 777bba6e3cbc52f9f1bd33c615d7da968cbbb2f9 SHA-256: f4b0d79748f50d34c806cd745237cea6c637bf030580bfb469848b353c13fb46
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1559.001 Component Object Model Hijacking

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 Equation Editor object is anomalous and carries a payload-like Ole10Native stream, strongly suggesting exploitation of CVE-2018-0798. This technique is commonly used to execute arbitrary code, leading to the download and execution of further malicious stages.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/PzSAY5.idx4 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
96b701b988761ed4e3932ef07b2b0eeb4822e72e4f0768c02a83e72533661f27		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/PzSAY5.idx4 1274368 bytes
ooxml_oleobject_00_ole10native_00.bin
9e533267d30acdcc54721eb69ac72efb8e5b8cace1f8fc4044aebea7b1ced151		 ole-package OOXML xl/embeddings/PzSAY5.idx4 Ole10Native stream: OLE10naTIvE 1261956 bytes

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