Office (OOXML) / .XLSX malware analysis — malicious · 003171d90aa2fc40

MALICIOUS

Office (OOXML) / .XLSX

89.7 KB Created: 2020-03-19 15:06:18 UTC Authoring application: Microsoft Excel 16.0300

MD5: ff09edacc883b1e29206b8d25fe1da07 SHA-1: b5fe04e2186f56c2590389ee1dae10d4bac1cb83 SHA-256: 003171d90aa2fc40f765d578ea82980fd4a8a1339cd042acd93a7a07dbd8a8d3

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet, which is a known method for executing malicious code within Office documents. While the macro content is truncated and obfuscated, its presence strongly suggests the file's purpose is to download and execute a secondary payload. No specific family could be identified due to the limited script visibility.

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` `d813dd6cdd6ad8f1300d9df50ed0dd1ec395477ae8623f3d14c4f84bfd38329e`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	22875 bytes

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