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

Static analysis result for SHA-256 54e285f369f0ba26…

MALICIOUS

Office (OOXML) / .XLSX

25.1 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 7e0f5d0a456e160a6a5ed2cd5b81529b SHA-1: 2278b2eff192d69dfc7753007dc61ac1de37bfab SHA-256: 54e285f369f0ba268f836631ee67245b621a1bc959cfc85b77e170c9d2b7e9e6
182 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1204.002 Malicious File: Malicious File T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros contain strings indicative of downloading and executing files, such as URLDownloadToFileA and ShellExecuteA. The reconstructed URL http://162.241.124.141/q/1.gif is likely used to fetch a second-stage payload. The presence of these elements strongly suggests a downloader attack pattern.

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. 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.
  • URL reconstructed from XLM cell array (1 URL) critical OOXML_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across individual numeric cells (one ASCII charcode per cell) or inside an embedded HTA that uses VBScript Chr()/&-concat obfuscation. The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF12 record stream of every worksheet and macrosheet part and decoding RK/inline-string cells in both row-major and column-major order.
  • 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://162.241.124.141/q/1.gif

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
7f348687a322ff0112303373edb2c858878ed1ba9e3aef350018df181f6c3d12		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 199937 bytes

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