Office (OOXML) / .XLSX malware analysis — malicious · d87db71ba3e3c4cd

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: ff8e34bc1a2b26b39f96224388f02935 SHA-1: 93abfb6bbe5a66f2e2a5dec73e2ea569c895e26a SHA-256: d87db71ba3e3c4cd1772e215bd836263756b6f6b3c8c36837ebd6ab0367bf5eb

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within an XLSX file. The extracted macro content, though partially obfuscated, reveals a path that appears to be an attempt to execute a file from 'C:\ProgramData\Microsoft Excel.exe'. This suggests the macro's purpose is to download and execute a malicious payload, a common technique for initial access or further system compromise.

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` `d34a4f13e484542d3ebf6ecef2ba9d212472e597c4579282921bee6ddf0f5be6`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	156811 bytes

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