Office (OOXML) / .XLSX malware analysis — malicious · cadb1a341e5306f3

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: cd50d342ea4d4fdee0795506c97fde53 SHA-1: 4214a68807e549523dbe957ccc59e9e5027c7d00 SHA-256: cadb1a341e5306f3bce87c13cc130b21947b511164824cf0458e9a9da06bf481

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Service Control T1204.002 Malicious File: User Execution

The critical heuristic firing indicates the presence of Excel 4.0 macros. The extracted macro content reveals a command that uses `wmic` to execute a file named 'excel.rtf' located in 'C:\ProgramData\'. This suggests the macro's purpose is to download and execute a second-stage payload, likely a malicious executable, from that location.

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` `70861d5253e1d3d839997ad73ba822ed6f5c38fb6a7ca2d2981b0d7f106a56ba`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	166286 bytes

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