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

Static analysis result for SHA-256 3d15a35a425ef81d…

MALICIOUS

Office (OOXML) / .XLSM

106.9 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: c8cdb2be4b6b0149c493a2e74b068c0b SHA-1: 72e707236e5eb6a8a76824cb3cabdb7a9432f19b SHA-256: 3d15a35a425ef81d74414ecea4c80bbc499c3c97ef62236ddaa396098fe8c8a6
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1105 Ingress Tool Transfer

This Excel macro-enabled spreadsheet (XLSM) contains Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. The presence of an Auto_Open defined name and the use of dangerous XLM functions like CALL and EXEC (OOXML_XLM_AUTOOPEN_DEFINEDNAME, OOXML_XLM_DANGEROUS_FN) strongly suggest the macro is designed to execute arbitrary code. The document body contains URLs that are likely used to download and execute a second-stage payload, aligning with the Ingress Tool Transfer (T1105) technique. The specific use of Excel 4.0 macros for execution points to the Malicious File (T1204.002) technique.

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
9cf577639483a84c18a4933d3e27f255a331eea77d6198cb6ba582a5fa65de0a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 240381 bytes

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