Office (OOXML) / .XLSX malware analysis — malicious · c6094f6a6be13243

MALICIOUS

Office (OOXML) / .XLSX

59.9 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: 4489af8c368a6772ad22b13cf5523aed SHA-1: 2ccdd4af8e39d7b35a7f316c0bb949e0c9ceda79 SHA-256: c6094f6a6be132436b483e6a99063ba6cc4f1e56de52100f3e6e8c8baf1631d8

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Service Execution

The sample is an Excel file containing a macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The extracted macro content reveals a command that uses `wmic` to execute a file named 'excel.rtf' located in the 'C:\ProgramData\' directory. This indicates the document's intent is to download and execute a second-stage payload. The family is unknown due to the generic nature of the payload execution.

Heuristics 1

Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET

Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `5585ee9c612d0bd244d27751b8680f2da95bfccfa46b24226bc5921923293ea8`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	63934 bytes

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