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

Static analysis result for SHA-256 23dd4c734599e8ff…

MALICIOUS

Office (OOXML) / .XLSX

63.8 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 95835b3c3655fb5d03a144486b4098b8 SHA-1: 1f59aabee795ba0c34f42bf8883307dcdf7dcf67 SHA-256: 23dd4c734599e8ff7f6e2d6e4ed51b760bf6f818b147d007aa03ddd8b61a9878
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The macro sheet contains obfuscated commands, including a path that appears to be a staging directory for a payload. The macro likely executes commands to download and run a second-stage payload from this location.

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
4f253d113671759b93f4d862a43d204e06bfb2e994705afa1cc893d4ee2f24f0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 4702 bytes

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