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

Static analysis result for SHA-256 743e3dd8b078b5ca…

MALICIOUS

Office (OOXML) / .XLSX

698.9 KB Created: 2023-08-03 11:34:29 UTC Authoring application: Microsoft Excel 16.0300
MD5: 300aed4f1f2dd5227c6304b4e3cb625f SHA-1: 28f59ac52042dd2ead402326bc1620da2f29ce1f SHA-256: 743e3dd8b078b5caa7316a6aed4997fb8e88212b56462333ed0948f6e186c77f
140 Risk Score

Malware Insights

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

The sample is a malicious XLSX file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor exploit. The heuristic firings indicate a NOP sled and an anomalous Ole10Native stream within the Equation Editor object, strongly suggesting it's designed to deliver and execute a secondary payload. The presence of an embedded OLE object and the exploitation of the Equation Editor point towards a common attack vector for delivering malware via spearphishing attachments.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/RHe.128JW contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • NOP sled detected high SC_NOP_SLED
    Found 20+ consecutive 0x90 bytes
  • 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
438bb1b003a0878e883c0b82c5e3e50cd0ea5c9b8148fd3167e02d427f2df780		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/RHe.128JW 989696 bytes
ooxml_oleobject_00_ole10native_00.bin
0fc587956d2fd8d2a614a53b7fabd14ed6b3ffb99bf72fb9af61c60ce9b8187d		 ole-package OOXML xl/embeddings/RHe.128JW Ole10Native stream: OLe10NAtiVe 979166 bytes

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