CVE-2019-19781 PoC — Citrix Application Delivery Controller和Citrix Systems Gateway 路径遍历漏洞

Description

Check your website for CVE-2019-19781 Vulnerable

介绍

# CVE-2019-19781-Checker
Check your website for CVE-2019-19781 Vulnerable

#VISIT https://citrix-checker.com TO CHECK IF YOU ARE VULNERABLE FOR CVE-2019-19781 


PLEASE USE OUR CHECKER TWO TIMES TO BE SURE


This website gives you the results if your service is vulnerable for CVE-2019-19781. There is a responder policy to mitigate the issue until there is a permanent fix.

To apply the fix login to the console or access it with putty and login. Default username: nsroot default password: nsroot

You can run the following codes after you succesfully logged in:
- enable ns feature responder
- add responder action respondwith403 respondwith "\"HTTP/1.1 403 Forbidden\r\n\r\n\""
- add responder policy ctx267027 "HTTP.REQ.URL.DECODE_USING_TEXT_MODE.CONTAINS(\"/vpns/\") && (!CLIENT.SSLVPN.IS_SSLVPN || HTTP.REQ.URL.DECODE_USING_TEXT_MODE.CONTAINS(\"/../\"))" respondwith403
- bind responder global ctx267027 1 END -type REQ_OVERRIDE
- save config

You can also apply it on the management interface by running the next commands:
- shell nsapimgr_wr.sh -ys skip_systemaccess_policyeval=0
- shell "echo 'nsapimgr_wr.sh -ys skip_systemaccess_policyeval=0' >> /nsconfig/rc.netscaler"
reboot


There is a few ways to identify that your maybe compromized or atleast a victim. Login again to the console or terminal and run the next commands and you will see dates + random files(like DxzXvx.xml) created.
shell
- ls -l /netscaler/portal/templates/
- ls -l /netscaler/portal/scripts/
- ls -l /var/tmp/netscaler/portal/templates/
- ls -l /var/vpn
- ls -l /var/vpns
- ls -l /etc/crontab
- cat  /etc/crontab


Not verified solution but perhaps it can minimize the effect:
Login to NS
start with: shell
chmod -R 700 /netscaler/portal/templates/
chmod -R 700 /netscaler/portal/scripts/
chmod -R 700 /var/tmp/netscaler/portal/templates/
chmod -R 700 /var/vpn/bookmark

chown -R root:wheel /netscaler/portal/templates/
chown -R root:wheel /netscaler/portal/scripts/
chown -R root:wheel /var/tmp/netscaler/portal/templates/
chown -R root:wheel /var/vpn/bookmark

The default permissions are mostly
- drwxr-xr-x 3 root wheel
or
- drwxr-xr-x 4 nobody wheel

There are also pentesters/white(ethical hackers)/grey hats which are also exploiting to see the impact and show companies that they are vulnerable.


We are using the vulnerability checker code of Trustedsec which is made by Rob Simon and David Kennedy.
If there is any questions you can contact info@senux-it.nl

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