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

Static analysis result for SHA-256 024464be59dd8b49…

MALICIOUS

Office (OOXML) / .XLSM

25.3 KB Created: 2021-03-11 11:19:51 UTC Authoring application: Microsoft Excel 16.0300
MD5: e09992868895642c981e39c929e2e43d SHA-1: b1d206d5ad45e31f90fb1767433143d9e1fdf115 SHA-256: 024464be59dd8b49c05768d200b17c7fdc14f1b863cbb8b0d6cc1d12be8ad056
182 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

This XLSM file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The macros utilize dangerous functions like FORMULA, which can call Win32 APIs to download and execute payloads. The presence of these macros suggests the file is designed to act as a downloader for further malicious activity.

Heuristics 4

  • 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: FORMULA 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.
  • 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
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
1aaf1f94e259a0874af050893367384b03c1e8bade3ee4961eb39675e6c91682		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 20637 bytes

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