Office (OOXML) / .XLSX malware analysis — malicious · dce2e3f42b29db4e

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: de7874ac8427f02702f8e2a58a3deae5 SHA-1: 66273158ff99d27fd8932dd26805a199e3083861 SHA-256: dce2e3f42b29db4e418cfd22153a38834e34bc2a391dc40dda39b878e58c87e0

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Service Execution

The file is an Excel 4.0 macro sheet, as indicated by the OOXML_XLM_MACROSHEET heuristic. The embedded macro attempts to execute a command using 'wmic process call create' to run 'mshta' with a specified file path. This suggests the macro's purpose is to download and execute a second-stage payload, likely disguised as 'excel.rtf', from the ProgramData directory.

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` `254ac317374edab68467f59b4fce3c97a519a7348fbe8e79e81ba373d854e0a2`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	109261 bytes

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