NSX-T is a Software-Defined-Networking (SDN) solution of VMware which, as its basic functionality, supports spanning logical networks across VMs on distributed ESXi and KVM hypervisors. The central controller of the SDN is the NSX-T Manager Cluster which is responsible for deploying the network configurations to the hypervisor hosts.
This summer, I looked into the mechanism which is used to add new KVM hypervisor nodes to the SDN via the NSX-T Manager. By tracing what happens on the KVM host, I discovered that the KVM hypervisor got instructed to download the NSX-T software packages from the NSX-T Manager via unencrypted HTTP and install them without any verification. This enables a Man-in-the-Middle (MITM) attacker on the network path to replace the downloaded packages with malicious ones and compromise the KVM hosts.
We recently came across an issue when playing around with VMware NSX-T which not anyone might be aware of when getting started with it. Because many of our customers start with transitioning to NSX-T, we want to share this with you. In short, the Distributed Firewall (DFW) of NSX-T can be easily bypassed in the default configuration because it only works effectively if at the same time, the SpoofGuard feature is enabled on all logical switch ports which is not the case by default.
Matthias and I had the pleasure to give a talk at the H2HC2018 in São Paulo, Brazil about attacking VMware NSX. The talk is an introduction to VMware NSX for security researchers, and it discusses possible attack vectors including the management, controlling, and data exchange planes. We demonstrated how to prepare a fuzzing and debugging setup for the ESXi kernel and the kernel modules. It should be noted that Olli was also supporting the research.
The slides can be found here.
During a recent customer project we identified several vulnerabilities in the VMware vRealize Automation Center such as a DOM-based cross-site scripting and a missing renewal of session tokens during the login. The vulnerabilities have been disclosed to VMware on November 20th, 2017. A security advisory for the vulnerabilities has been made available here on April 12th, 2018.
Just a few words regarding the cross-site scripting vulnerability. This vulnerability is present within a GET request to the URL /vcac/gadgets/ifr because of certain URL parameters whose values are directly passed to an eval function call. The vulnerable parameters are gwt:onLoadErrorFn and gwt:onPropertyErrorFn. It seems that these parameters are actually never used by the application and we only found them by looking at the source code.
Yesterday 7Elements released the description of a Remote Code Execution vulnerability in VMware vCenter. The information came in at a good point as I’m at the moment drafting a follow-up blogpost for this one which will summarize some of our approaches to virtualization security. The vCenter vulnerability is both quite critical and particularly interesting in several ways:
Once there is proper network isolation & restriction, the vulnerability should not be exploitable from the overall corporate network (or maybe even the Internet — a quick inaccurate shodan search for “vcenter” returned about 1800 results and at random checks actually revealed vCenter systems). It should also not be exploitable from ESXi hosts managed through the vCenter: ESXi hosts need to be able to connect to the vCenter for heartbeat messages, however “only” on ports 443 and 902 — the vulnerability exploits a service running on TCP ports 9875 – 9877.
It is questionable whether the exploited Java RMI functionality is really required for the operation of VMware infrastructures. This blogpost provides further detail on the known type of vulnerability in Java applications. VMware had a similar issue back in 2010, where their workaround to fix a vulnerability was to just disable the affected component, resulting in the impression that it wasn’t even required in the first place. Let’s see whether the future will bring up more vulnerabilities which could have been prevented by implementing more thorough hardening of all components (e.g. following the minimal machine principle). Furthermore in 2011 there was a similar 3^(rd) party component vulnerability in vCenter which we covered in this blogpost. The totality of our posts on VMware security can be found here.
For high-security environments we have been recommending for some time to use a dedicated vCenter per hypervisor cluster (i.e. if you have two hypervisor clusters, one for internal and one for DMZ systems, you should use two separate vCenter systems). Vulnerabilities like these illustrate the need for that, given that the ESXi hosts need to be able to access the vCenter on the network level.
While fairytales often start with “Once upon a time…”, our blogposts often start with “During a recent security assessment…” — and so does this one. This time we were able to spend some time on VMware’s vCenter Operations Manager (herein short: VCOPS). VCOPS is a monitoring solution for load and health of your vSphere environment. In order to provide this service, two virtual machines (analytics engine and Web-based UI) must be deployed (as a so-called vApp) that are configured on startup by various scripts (mainly /usr/lib/vmware-vcops/user/conf/install/firstbootcommon.sh) to match the actual environment and communicate via an OpenVPN tunnel that is established directly between the two machines. To gather the monitoring data, read-only access to the vCenter is required.
In the course of our virtualization research, we came across a certain technical issue we couldn’t find an easy solution on knowledge bases and the like. However, as we found the question several times on the web, the following post gives just a short hint on a technical detail.
If you want to connect two virtual machines in VMware Fusion using a serial port (e.g. for debugging purposes), Fusion doesn’t provide you an GUI option to configure that. However, if you just add the following config to the debugger system’s VMX file:
In our last series of posts regarding the VMDK file inclusion attack, we focused on read access and prerequisites for the attack, but avoided stating too much about potential write access. But as we promised to cover write access in the course of our future research, the following post will describe our latest research results.
First of all, the same prerequisites (which will be refined a little bit more later on) as for read access must be fulfilled and the same steps have to be performed in order to carry out the attack successfully. If that is the case, there are several POIs (Partitions Of Interest) on a ESXi hypervisor that are interesting to include:
As announced at last week’s #HITB2012AMS, I’ll describe the fuzzing steps which were performed during our initial research. The very first step was the definition of the interfaces we wanted to test. We decided to go with the plain text VMDK file, as this is the main virtual disk description file and in most deployment scenarios user controlled, and the data part of a special kind of VMDK files, the Host Sparse Extends.