Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 a4280a8378cb539b…

MALICIOUS

Office (OOXML) / .XLSX

117.6 KB Created: 2021-03-29 19:56:22 UTC Authoring application: Microsoft Excel 16.0300
MD5: e45bd6fe5e086fd4adff5843d008eba9 SHA-1: 482fbb859bf57acd7860cc5a7983ed266ce7f6e4 SHA-256: a4280a8378cb539b9011c042b87abd2939a372f3775c60a582d5c12c40746539
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing a macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The embedded Excel 4.0 macro sheet is heavily obfuscated and truncated, preventing a detailed analysis of its specific actions. However, the presence of this macro sheet strongly suggests an intent to execute arbitrary commands upon opening.

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.

FilenameKindSourceSize
xlm_sheet_00.bin
90e3c112758212d140c3555d2719228954db231aa00ca67e85dab1e2f4a975ad		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 91649 bytes

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