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

Static analysis result for SHA-256 c5af58dc5cc84997…

MALICIOUS

Office (OOXML) / .XLSM

106.9 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 98b64b559916fe0cd422fdc1cc8f4d03 SHA-1: 1374d3fe9761f3d6ea7019fe7e186b71e8bc8fd2 SHA-256: c5af58dc5cc84997117cb10cef2a42ab18c74ecd244735d2cef04fbf12fd08a2
180 Risk Score

Malware Insights

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

The sample is an XLSM file containing Excel 4.0 macros. The macros utilize dangerous functions like CALL and EXEC, indicating an attempt to download and execute a second-stage payload from the provided URLs. The document body contains obfuscated text that appears to be part of the macro's logic, further supporting the malicious intent.

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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