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

Static analysis result for SHA-256 bcfa86f788a1354d…

MALICIOUS

Office (OOXML) / .XLSM

84.2 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 181a8b9767efd34da4e7d185fc24086e SHA-1: 6a9c95df120613b3194cd8be1348e22a38b4e6c9 SHA-256: bcfa86f788a1354dbd3ab8445a2a7b9156ecae68552a2f4ece34bcf25497fffd
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The file contains Excel 4.0 macros, indicated by the 'OOXML_XLM_MACROSHEET' and 'OOXML_XLM_AUTOOPEN_DEFINEDNAME' heuristics. Crucially, the 'OOXML_XLM_DANGEROUS_FN' heuristic flags the use of dangerous functions like CALL and EXEC, which are known primitives for downloading and executing payloads. The document body contains multiple URLs that are likely the sources for these payloads. The script's intent is to download and execute a second-stage payload from one of the provided URLs.

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: CALL, EXEC, FORMULA.FILL, 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.
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
6bb1fa7b25c4a31dd2d66243f24bc2b4809a5ecf6b1ca9480c724b6e46bd7687		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 238359 bytes

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