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

Static analysis result for SHA-256 155a1cc7d02dd1f0…

MALICIOUS

Office (OOXML) / .XLSM

81.8 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 0b90a89785edd94e2699c7f8ec53f69b SHA-1: abb827a045aa13ae9a719bb4d13c11eadbc674bd SHA-256: 155a1cc7d02dd1f05d338577d29d1dad20660ee877c3c5be5d5c4298a7ab57ab
182 Risk Score

Malware Insights

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

The sample is an XLSM file containing Excel 4.0 macros, which is a strong indicator of malicious intent. The macros utilize dangerous functions like CALL and EXEC, which are known to be used for downloading and executing arbitrary code. The embedded URLs, such as http://halle-auer20h.ru.com/lenta.html, are likely the sources for these payloads. The use of these functions and the presence of external URLs strongly suggest an attack pattern aimed at delivering and executing a secondary malicious component.

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: EXEC, HALT, CALL, WORKBOOK.HIDE 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 https://steilppm.ac.id/drms/lenta.html
    • https://acienciaparaficarrico.com.br/drms/lenta.html
    • https://deccanrestaurant.co.uk/drms/lenta.html
    • http://halle-auer20h.ru.com/lenta.html
    • 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
689e62f11cd6435ca34ee626a16f1d01b31a5e5ccf3ae7db3a2ae524feaebaa6		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 7541 bytes

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