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

Static analysis result for SHA-256 f0f4c6cdb0748785…

MALICIOUS

Office (OOXML) / .XLSX

682.2 KB Created: 2013-09-06 09:04:58 UTC Authoring application: Microsoft Excel 15.0300
MD5: b959fb2dad35484c3199fbdc66b9885d SHA-1: b83a95ece20b7daf64b8d28b1ecac8240498bf86 SHA-256: f0f4c6cdb07487858da76e2275c4d0adfe1ee5ffb09c63b7c12c8446a2b02d5d
120 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1559.001 Component Object Model Hijacking T1027 Obfuscated Files or Information

The sample is an Office Open XML spreadsheet 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, suggesting it's being used to exploit a vulnerability. This technique is commonly used to deliver second-stage malware. The embedded OLE object and the specific stream name are included as IOCs.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/wKTqE.UwlxqRm 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.
  • External relationship medium OOXML_EXTERNAL_REL
    External target in xl/externalLinks/_rels/externalLink4.xml.rels: /Eko/R3_Prod.rapport/Hanaskog/HSKG00xx/Produktionsrapport Hanaskog 0001.xls
  • 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
4a6451f15ac47272f191484eb5d81e2be8726cde62971ee90af8853c236c433f		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/wKTqE.UwlxqRm 960000 bytes
ooxml_oleobject_00_ole10native_00.bin
738e6d2f70d1a66a6385ff7230d746100b52aa18e5529bdde8a43233cbc61c74		 ole-package OOXML xl/embeddings/wKTqE.UwlxqRm Ole10Native stream: ole10NATiVE 950115 bytes

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