安全研究
安全漏洞
Asterisk IAX2报文放大远程拒绝服务漏洞
发布日期：2008-04-23
更新日期：2008-04-24
受影响系统：
Asterisk Asterisk 1.4.x不受影响系统：
Asterisk Asterisk 1.2.x
Asterisk Asterisk 1.0.x
Asterisk Business Edition C.x.x
Asterisk Business Edition B.x.x
Asterisk Business Edition A.x.x
Asterisk AsteriskNOW 1.0.x
Asterisk Appliance Developer Kit 0.x.x
Asterisk s800i 1.0.x
Asterisk Asterisk 1.4.20描述：
Asterisk Asterisk 1.2.28
Asterisk Business Edition C.1.8.1
Asterisk Business Edition B.2.5.2
Asterisk AsteriskNOW 1.0.3
Asterisk s800i 1.1.0.3
BUGTRAQ ID: 28901
CVE(CAN) ID: CVE-2008-1897
Asterisk是开放源码的软件PBX，支持各种VoIP协议和设备。
Asterisk在处理呼叫的机制上存在漏洞，远程攻击者可能利用此漏洞对第三方机器执行拒绝服务攻击。
IAX2协议允许IC_NEW报文启动呼叫。IC_NEW报文是18字节长的UDP报文，而呼叫可能非常长，包含有很多数据。由于UDP是可以伪造的，因此远程攻击者可以在IAX2握手期间欺骗IAX2握手，导致Asterisk服务器向目标发送大量数据，造成网络堵塞。
<*来源：Tilghman Lesher （tlesher@digium.com）
链接：http://secunia.com/advisories/29927/
http://bugs.digium.com/print_bug_page.php?bug_id=10078
https://www.altsci.com/concepts/page.php?s=asteri&p=2
http://marc.info/?l=bugtraq&m=120896337203016&w=2
http://www.debian.org/security/2008/dsa-1563
*>
测试方法：
警 告
以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！
https://www.altsci.com/concepts/altsci_iax2-0.6.tgz
建议：
临时解决方法：
* 禁止远程未经认证的IAX2会话。
厂商补丁：
Debian
------
Debian已经为此发布了一个安全公告（DSA-1563-1）以及相应补丁:
DSA-1563-1：New asterisk packages fix denial of service
链接：http://www.debian.org/security/2008/dsa-1563
补丁下载：
Source archives:
http://security.debian.org/pool/updates/main/a/asterisk/asterisk_1.2.13~dfsg-2etch4.dsc
Size/MD5 checksum: 1488 5f5e9573d490427c5a69a10aa97f158b
http://security.debian.org/pool/updates/main/a/asterisk/asterisk_1.2.13~dfsg.orig.tar.gz
Size/MD5 checksum: 3835589 f8ee088b2e4feffe2b35d78079f90b69
http://security.debian.org/pool/updates/main/a/asterisk/asterisk_1.2.13~dfsg-2etch4.diff.gz
Size/MD5 checksum: 183285 26bd25ccb154a4ad32980d943b986b77
Architecture independent packages:
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-doc_1.2.13~dfsg-2etch4_all.deb
Size/MD5 checksum: 1500302 8bdb0c668d19cfa10a1a21e18b404abf
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-web-vmail_1.2.13~dfsg-2etch4_all.deb
Size/MD5 checksum: 73970 b58221f4979cc030855181025a912e88
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-config_1.2.13~dfsg-2etch4_all.deb
Size/MD5 checksum: 131882 4e51e2e9df2c8815b7f73de4366d1226
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-sounds-main_1.2.13~dfsg-2etch4_all.deb
Size/MD5 checksum: 1504806 aba4a61bee8550ce08491ca99e20daed
http://security.debian.org/pool/updates/main/a/asterisk/asterisk_1.2.13~dfsg-2etch4_all.deb
Size/MD5 checksum: 146714 8b47af29382b0fd93ba9276c6d130a9b
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-dev_1.2.13~dfsg-2etch4_all.deb
Size/MD5 checksum: 170154 6db4874707b5e4bcaac7daf6d8f52c2b
alpha architecture (DEC Alpha)
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_alpha.deb
Size/MD5 checksum: 1902278 7f85e13bc5fcbe4e97b1c38cda233dac
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_alpha.deb
Size/MD5 checksum: 137358 2b182763234ee7c8ad32eb88ab1d7439
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_alpha.deb
Size/MD5 checksum: 1938542 0e3d8bcf8c3d417d76dcec6d18c54aa8
amd64 architecture (AMD x86_64 (AMD64))
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_amd64.deb
Size/MD5 checksum: 133398 ed20b24f1a2f341bd6d4e028ce59a90c
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_amd64.deb
Size/MD5 checksum: 1780430 8ce4d0f0065fbda1b8b6faf452aa8cf1
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_amd64.deb
Size/MD5 checksum: 1745772 c7e3f3533bd980e6cf4fae76a7fe53a6
arm architecture (ARM)
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_arm.deb
Size/MD5 checksum: 1702038 c21d7d8f2a6a22340c6c532c52297238
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_arm.deb
Size/MD5 checksum: 136578 e058fda61addca152ebcef309ed53db0
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_arm.deb
Size/MD5 checksum: 1668554 be43593d0db307fff5d9233d99f8683d
hppa architecture (HP PA RISC)
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_hppa.deb
Size/MD5 checksum: 1859784 e01288aa37bf6d1021836e4750896192
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_hppa.deb
Size/MD5 checksum: 1899426 4dca3a75e206580153fac43f4a16d9ac
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_hppa.deb
Size/MD5 checksum: 145500 c349640da06db141cc1bdeae512426a2
i386 architecture (Intel ia32)
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_i386.deb
Size/MD5 checksum: 1650280 3de468a3ac7da9765b67a3637eaf0c8b
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_i386.deb
Size/MD5 checksum: 1616900 cde58be5158607a6d55ffedf8f5f6b99
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_i386.deb
Size/MD5 checksum: 131104 fe4e96f50604b2ce1b5c1ed2e80ee0e2
ia64 architecture (Intel ia64)
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_ia64.deb
Size/MD5 checksum: 2349674 6fd62f264d405873e44ba0a08a58b719
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_ia64.deb
Size/MD5 checksum: 149858 b9ab483687ffa690c90720ef1dce7a33
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_ia64.deb
Size/MD5 checksum: 2395734 cfbb272cc6da385b4b144bd1a2877ec8
mips architecture (MIPS (Big Endian))
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_mips.deb
Size/MD5 checksum: 130344 589d8d4e2341901d52cea2c7f7688368
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_mips.deb
Size/MD5 checksum: 1688936 26b6d9c89013f575a8e12559fd525a99
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_mips.deb
Size/MD5 checksum: 1720586 3a4ece7c7ca3dce1a7449bae6da3b468
mipsel architecture (MIPS (Little Endian))
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_mipsel.deb
Size/MD5 checksum: 129852 65fa3add41986df9af5ae6da47ce754b
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_mipsel.deb
Size/MD5 checksum: 1664436 06838223a31772f671cc5bd5063c0125
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_mipsel.deb
Size/MD5 checksum: 1696490 ce4a77d18c64e90d0803730661b08f8c
powerpc architecture (PowerPC)
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_powerpc.deb
Size/MD5 checksum: 1825754 da384bd468577fa5058ff4547e97fb1f
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_powerpc.deb
Size/MD5 checksum: 133228 d05176705d1236ca9e039a05fd537f15
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_powerpc.deb
Size/MD5 checksum: 1864110 d20124ef308de4354b5ab0d53f5d22a7
s390 architecture (IBM S/390)
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_s390.deb
Size/MD5 checksum: 1744918 0ff79d065ecc670dd6a8b36f76654494
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_s390.deb
Size/MD5 checksum: 136738 ebc38fa1031636449198da18f2542df7
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_s390.deb
Size/MD5 checksum: 1780914 bc075c8673bc6a48d09d3872e9f1a4fd
sparc architecture (Sun SPARC/UltraSPARC)
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-classic_1.2.13~dfsg-2etch4_sparc.deb
Size/MD5 checksum: 1632652 7341c9d19478d655acaa94c3a36c3cd0
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-bristuff_1.2.13~dfsg-2etch4_sparc.deb
Size/MD5 checksum: 1664570 6824b18d4424ec863a96763bf90184b9
http://security.debian.org/pool/updates/main/a/asterisk/asterisk-h323_1.2.13~dfsg-2etch4_sparc.deb
Size/MD5 checksum: 132348 1759eab6abaa0ab551bf722656d9debf
补丁安装方法：
1. 手工安装补丁包：
首先，使用下面的命令来下载补丁软件：
# wget url (url是补丁下载链接地址)
然后，使用下面的命令来安装补丁：
# dpkg -i file.deb (file是相应的补丁名)
2. 使用apt-get自动安装补丁包：
首先，使用下面的命令更新内部数据库：
# apt-get update
然后，使用下面的命令安装更新软件包：
# apt-get upgrade
Asterisk
--------
目前厂商已经发布了升级补丁以修复这个安全问题，请到厂商的主页下载：
http://www.asterisk.org/
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