title: Citrix Netscaler Attack CVE-2019-19781
id: ac5a6409-8c89-44c2-8d64-668c29a2d756
status: experimental
description: Detects CVE-2019-19781 exploitation attempt against Citrix Netscaler, Application Delivery Controller and Citrix Gateway Attack
author: Arnim Rupp, Florian Roth
date: 2020/01/02
modified: 2020/09/03
references:
    - https://support.citrix.com/article/CTX267679
    - https://support.citrix.com/article/CTX267027
    - https://isc.sans.edu/diary/25686
    - https://twitter.com/mpgn_x64/status/1216787131210829826
    - https://github.com/x1sec/x1sec.github.io/blob/master/CVE-2019-19781-DFIR.md
logsource:
    category: webserver
    definition: 'Make sure that your Netscaler appliance logs all kinds of attacks (test with http://your-citrix-gw.net/robots.txt). The directory traversal with ../ might not be needed on certain cloud instances or for authenticated users, so we also check for direct paths. All scripts in portal/scripts are exploitable except logout.pl.'
detection:
    selection:
        c-uri: 
            - '*/../vpns/*'
            - '*/vpns/cfg/smb.conf'
            - '*/vpns/portal/scripts/*.pl*'
    condition: selection
fields:
    - client_ip
    - vhost
    - url
    - response
falsepositives:
    - Unknown
level: critical
tags:
    - attack.initial_access
    - attack.t1190