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

Static analysis result for SHA-256 0e9e4bfbbeeb52f3…

MALICIOUS

Office (OOXML) / .XLSM

268.2 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 42ad80007a77fdea4d1540e835690e20 SHA-1: fe167abef2eb8be8ab184dcd5b188c8ef0b665b6 SHA-256: 0e9e4bfbbeeb52f3fd180edb57a32fa214cd112d44e5acb7aa5e25b4fbc9a36b
190 Risk Score

Malware Insights

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

The file is an XLSM document containing Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like EXEC and FOPEN to download and execute a script file located at 'C:\ProgramData\nJzRHFNPUUGt.sct'. This indicates a downloader or dropper functionality, aiming to execute a second-stage payload.

Heuristics 5

  • 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: FOPEN, FWRITE, FCLOSE, EXEC, 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.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
9a8d1a69bb048c9496c80e381690eef6998e51f5b5b0d340f1854faa4ace7fab		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 866868 bytes

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