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

Static analysis result for SHA-256 711a05c2b42db934…

MALICIOUS

Office (OOXML) / .XLSM

430.4 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 15.0300
MD5: 0b49c3bd2479bed644ee5f0a21bdeabb SHA-1: 2f63381e01e5c6c2dd0b2759a645c7aae6019a49 SHA-256: 711a05c2b42db93458407fc8d81cdd8d5c92a5cf44e5cab4e9ca58f5267d3cab
242 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The file is an Excel macro-enabled spreadsheet (XLSM) containing Excel 4.0 macros. These macros utilize dangerous functions like REGISTER and HALT, along with WinAPI calls such as CreateDirectoryA and DownloadToFileA, to download and execute a second-stage payload from the URL http://213.252.247.240/fr-pot/lsas.exe. The presence of these functions and API calls strongly indicates a downloader or droppper functionality.

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: REGISTER, 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.
  • 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.
  • 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://213.252.247.240/fr-pot/
    • http://213.252.247.240/fr-pot/lsas.exe
    • http://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
9a3a62f80dcf724ed6500da2c56082c372b86eb06812511d597c2b0a14dda8e4		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1971525 bytes

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