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

Static analysis result for SHA-256 814618c68667b039…

MALICIOUS

Office (OOXML) / .XLSM

81.8 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 7531766e55b4311b5d2150440a5fd3fa SHA-1: a48a13da77451ccd9d382cd6990971c450ae56d6 SHA-256: 814618c68667b03933a8e2c199a4d30093d82b688d89163effe5028bcc44e89c
182 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The sample is an Excel macro-enabled spreadsheet (XLSM) containing Excel 4.0 macros. Critical heuristics indicate the use of dangerous XLM formula APIs like CALL and EXEC, which are commonly used to download and execute payloads. The macros likely leverage the embedded URLs to fetch a second-stage malicious file. The presence of Auto_Open and the use of dangerous functions strongly suggest a downloader functionality.

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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