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

Static analysis result for SHA-256 76c24f48f328ccac…

MALICIOUS

Office (OOXML) / .XLSM

325.4 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: d32fcbe77518b3c277c992a6738c6148 SHA-1: 4a0a4db03a78fc0c2f2ce6fecacc94303322fcdd SHA-256: 76c24f48f328ccac2edb7e0685cbfd346a3fdf0b95c2778a23aaadf4cde3f053
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell

This XLSM file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like FOPEN, FWRITE, FCLOSE, EXEC, and CALL to write and execute a script file to disk. Specifically, the macro constructs the path 'C:\ProgramData\qqsxgcl.sct' and uses FOPEN to prepare it for writing. The subsequent use of EXEC indicates an attempt to run the created script, likely to download and execute a second-stage payload. The confidence is high due to the direct use of these dangerous functions and the construction of a file path for execution.

Heuristics 5

  • 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.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: FOPEN, FWRITE, FCLOSE, EXEC, HALT critical OOXML_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
4585580eb857523620edb0c11bdfc04892769214267e6015182e1f93da37851d		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1631601 bytes

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