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

Static analysis result for SHA-256 1869477c20e7b6fd…

MALICIOUS

Office (OOXML) / .XLSX

24.5 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 8b5dd0e15a2f039b02b357e9c71cba41 SHA-1: a21882a2d38cab64a9fccaca64c542783a340139 SHA-256: 1869477c20e7b6fdca75bf2cbb28e3b9778fbb5cfac99b3c6e5a8b213e34aaea
120 Risk Score

Malware Insights

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

The file contains embedded Excel 4.0 macros, which are known to be used for malicious purposes. The heuristics indicate the presence of WinAPI and download strings such as URLDownloadToFileA and ShellExecuteA, suggesting the macro's intent is to download and execute a second-stage payload. The specific download and execution functions strongly indicate an Ingress Tool Transfer (T1105) attack pattern.

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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