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

Static analysis result for SHA-256 4ae1d60605bf439b…

MALICIOUS

Office (OOXML) / .XLSX

24.5 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: b4bbe61de074073b504799ba104d455c SHA-1: 903b7ef16c1d85527f642ea89a871e23f2063e6e SHA-256: 4ae1d60605bf439b81ad675fd4bdeb7839ff5fc4c84ce09656cb97938dd67d93
120 Risk Score

Malware Insights

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

The file contains an Excel 4.0 macro sheet, indicated by the OOXML_XLM_MACROSHEET heuristic. This macro sheet includes strings related to WinAPI functions such as URLDownloadToFileA, DownloadToFileA, ShellExecuteA, and CreateDirectoryA, suggesting it is designed to download and execute a second-stage payload. The OOXML_XLM_BINARY_WINAPI_STRINGS heuristic further supports this, noting the presence of download-related strings and potential executable paths. The specific functions identified point towards a downloader or droppper malware.

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

Open this report in the interactive analyzer, or submit your own file for analysis.