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

Static analysis result for SHA-256 4aa2c5c031bbc638…

MALICIOUS

Office (OOXML) / .XLSM

105.3 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 9cc2257d286fb8949f561ff60fdddbe7 SHA-1: e3f3af8f4805d2f1b388fd64d25f4996113aa839 SHA-256: 4aa2c5c031bbc638d541dedac418fc73577a6c9a485464335d99296d4cc59bee
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1204.002 Malicious File: 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 payload from the URL found in the document body. The presence of an Auto_Open macro further suggests automatic execution upon opening the document.

Heuristics 4

  • Excel 4.0 macro sheet (3 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, FORMULA.FILL, HALT, EXEC 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
8370a1e92b107cad91ec54d5d2d7e2416067b15c03d5df1c91be01a243e1ce47		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 16586 bytes
xlm_sheet_01.xml
948993c6fc5565479e84f819dcc42810248e35f653f9052b11673c0c5157eb9b		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1084 bytes
xlm_sheet_02.xml
1d574875047613d4002c2621fc25a83f69a8a88701bce35c44925e78d9fa4338		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 209966 bytes

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