Office (OOXML) / .XLSX malware analysis — malicious · e48e4e8424294d3d

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: d9c8319abdbf4c7712d180e30c04afb6 SHA-1: 115ccb13c988e395c13e8ff06ec6e4965805fb38 SHA-256: e48e4e8424294d3d8ed14741b8d52730db273a1b33e9e6ad2a0f23cec65d9352

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Service Execution

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet. The extracted script content reveals a WMIC command that executes 'mshta' to create and likely execute a file named 'excel.rtf' from the 'C:\ProgramData\' directory. This suggests the macro's purpose is to download and execute a second-stage payload.

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` `95b5dcaff6744f055ff2cef22d2f49bb4b73c4a5b8944d3772d531298971ca17`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	170585 bytes

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