Simon's Citricks

Daniel Weppeler postet a link on how to activate Citrix Logging for Exploit 1 and 2: https://twitter.com/_DanielWep/status/1217022904073801728 #CVE201919781 #Citrix Create MessageAction: add audit messageaction MsgAct_CVE WARNING "\"CVE Attack from IP \"+CLIENT.IP.SRC+\" - URL: \"+HTTP.REQ.URL.PATH.HTTP_URL_SAFE+\" (headers: \"+HTTP.REQ.FULL_HEADER.HTTP_HEADER_SAFE+\")\"" -logtoNewnslog YES Enable userDefinedAuditlog: set audit syslogParams -logLevel ALL -userDefinedAuditlog YES set audit nslogParams -logLevel ALL -userDefinedAuditlog YES Bind #Syslog Message Action to CVE Responder Policy: set responder policy ResPol_Fix_CVE-2019-19781 -logAction MsgAct_CVE

You can check if your NetScaler is affected by CVE-2019-19781 with following commands: Indicators of compromise To get an idea wether your Citrix ADC is compromised I’d recommend to perform (at least!) the following steps Template files The exploits all write files to two different directories. Scan those via: shell ls /netscaler/portal/templates/*.xml shell ls /var/tmp/netscaler/portal/templates shell ls /var/vpn/bookmark/*.xml If you find files similar to the following you are likely to be compromised Apache Log files In addition, attempts to exploit the system leave traces in the Apache httpaccess log files. Those you can validate via: shell cat /var/log/httpaccess.log | grep vpns | grep xml shell cat /var/log/httpaccess.log | grep "/\.\./" shell gzcat /var/log/httpaccess.log.*.gz | grep vpns | grep xml shell gzcat /var/log/httpaccess.log.*.gz | grep "/\.\./" The following output is found on a system that was exploited: Howev...

Information from Citrix Technology Professional Matthias Schlimm: Hello everybody,   An additional vulnerability was found in 2 HTTP HEADERN today, following CVE-2019-19781 from December 2019, i.e. All systems that have already passed the "Mitgation Steps from article https://support.citrix.com/article/CTX267679" cannot avoid making another change. Unfortunately, there is currently no official blog or supplement from Citrix available, so I can only share what I have received from Citrix sources here:     --snip --- There is a new attack against the CVE, it seems like it can exploit using 2 headers. You can read more about here: https://isc.sans.edu/forums/diary/Citrix+ADC+Exploits+are+Public+and+Heavily+Used+Attempts+to+Install+Backdoor/25700/I’ve updated my responder policy expression with:   HTTP.REQ.URL.DECODE_USING_TEXT_MODE.CONTAINS (“/ vpns /“) && (! CLIENT.SSLVPN.IS_SSLVPN || HTTP.REQ.URL.DECODE_USING_TEXT_MODE.CONTAINS (“/../“)) || http.req.hea...