CAMSCTF CCTF 2015: Excel Data (Forensics) Write-up

Description:

Ever wonder why your homework gets corrupted so easily?

Solution: 
          Forensic challenge, In basically I try strings and grep command to find something. xD

root@ubuntu:~# file excel_data.xlsx 
excel_data.xlsx: Zip archive data, at least v1.0 to extract
root@ubuntu:~# strings excel_data.xlsx | grep "flag"
xl/charts/flag.txt
xl/charts/flag.txt
root@ubuntu:~# mv excel_data.xlsx excel_data.zip
root@ubuntu:~# unzip excel_data.zip 
Archive:  excel_data.zip
   creating: docProps/
  inflating: docProps/app.xml        
  inflating: docProps/core.xml       
   creating: xl/
  inflating: xl/calcChain.xml        
   creating: xl/charts/
  inflating: xl/charts/chart1.xml    
  inflating: xl/charts/chart2.xml    
  inflating: xl/charts/flag.txt      
   creating: xl/drawings/
  inflating: xl/drawings/drawing1.xml  
  inflating: xl/drawings/drawing2.xml  
   creating: xl/drawings/_rels/
  inflating: xl/drawings/_rels/drawing1.xml.rels  
  inflating: xl/drawings/_rels/drawing2.xml.rels  
  inflating: xl/sharedStrings.xml    
  inflating: xl/styles.xml           
   creating: xl/theme/
  inflating: xl/theme/theme1.xml     
  inflating: xl/workbook.xml         
   creating: xl/worksheets/
  inflating: xl/worksheets/sheet1.xml  
  inflating: xl/worksheets/sheet2.xml  
  inflating: xl/worksheets/sheet3.xml  
  inflating: xl/worksheets/sheet4.xml  
   creating: xl/worksheets/_rels/
  inflating: xl/worksheets/_rels/sheet2.xml.rels  
  inflating: xl/worksheets/_rels/sheet3.xml.rels  
   creating: xl/_rels/
  inflating: xl/_rels/workbook.xml.rels  
  inflating: [Content_Types].xml     
   creating: _rels/
  inflating: _rels/.rels             
root@ubuntu:~# cat xl/charts/flag.txt 
{iT's_r1gh7_h3r3}
root@ubuntu:~#

Flag: {iT's_r1gh7_h3r3}