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

Static analysis result for SHA-256 1d700dece40d52ae…

MALICIOUS

Office (OOXML) / .XLSX

80.3 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 210573e41374cd2d5cd26436cde6aac2 SHA-1: d9bc3ba76bb669dc90ac1c1b2d519a97d88d7f39 SHA-256: 1d700dece40d52ae1a1ced0e9d561b1ae5c641b9c17a1599cd554b408d385dac
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. The macro sheet appears to contain obfuscated strings that, when reconstructed, point to a path 'C:\ProgramData\excel.rtf'. This suggests the macro's purpose is to execute commands, likely to download and run a second-stage payload from this location. The family is unknown due to the lack of specific indicators.

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
e50c3645964b35a02425952590fbaea378f0eed3acf901a109b507d82315a72c		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 127575 bytes

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