Office (OOXML) / .XLSX malware analysis — malicious · c60ec928944650f2

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: c1327de05c96212baa5698fbb2f66853 SHA-1: 8c871cba2740ae6bd3eb5b0968f6a7163700a294 SHA-256: c60ec928944650f2ad4d3a466ae75f905f3779997fd6bfd46cdf9fb4e0d71b6b

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Service Execution

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. Analysis of the embedded macro sheet reveals attempts to construct a path to 'C:\ProgramData\System\System.exe', suggesting the macro's purpose is to execute a payload from this location. This is a common technique for initial access or downloading further stages of malware.

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` `c04ea95f5b0a13e2fbd8b37e917ff7110f47c3edd40479f24972eafac1e84fc3`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4619 bytes

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