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

Static analysis result for SHA-256 2f3098bacc2af729…

MALICIOUS

Office (OOXML) / .XLSX

24.5 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 94eeacc6caf1761d2a15cf2d9b17437d SHA-1: 34cd6d3dec8100c169ae54ad056aefd347915d38 SHA-256: 2f3098bacc2af7299fd4835cba2304f09351ce7de8cd484b8c14c7c8e39cfbf0
120 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample contains critical heuristic firings indicating the presence of Excel 4.0 macros that utilize WinAPI functions for downloading and executing files. Specifically, the macros leverage functions like URLDownloadToFileA and ShellExecuteA, suggesting an intent to download and run a second-stage payload. The presence of these functions and the file type strongly indicate a malicious document designed for initial payload delivery.

Heuristics 2

  • 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. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
  • Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS
    Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
99a6a52acb8f5c734f6d86faf89e0637a94ac99f953aa583d2658b47d2e1f9b9		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 194023 bytes

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