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

Static analysis result for SHA-256 6f21919bded2cd19…

MALICIOUS

Office (OOXML) / .XLSM

660.7 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 3268f511879621f300eb99d1d3517a9d SHA-1: 65474cc65c769c444a010bd23f8a1d0ecc9cb0d0 SHA-256: 6f21919bded2cd197c66a8ca7db6fa0867757c30048d57677e655185c2aca65b
190 Risk Score

Malware Insights

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

This Excel macro-enabled workbook (.XLSM) utilizes Excel 4.0 macros, which are known for their ability to execute arbitrary code. The macros employ dangerous functions like REGISTER and EXEC to download and run a second-stage payload, specifically referencing 'regsvr32 ..\Kro.fis'. The embedded URLs likely serve as sources for this payload. The use of hidden sheets and the Auto_Open defined name further indicate malicious intent.

Heuristics 5

  • Excel 4.0 macro sheet (2 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, RUN, EXEC, 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.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 4 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • 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://104.168.166.222/images/darkmoonlite.png
    • http://104.168.166.222/images/shortearthget.png
    • http://104.168.166.222/images/lovemetertok.png
    • 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
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
40ddb28feb0f81c4ec854fd8ba2b194a30a086ab4790b6dad4d44c8b8ae4ad9f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 2083 bytes
xlm_sheet_01.xml
24a9abf86273767cb6dc3ef5123101e29e32d244c5f84ae5cf491b44ffd6397a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1651 bytes

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