Question About Using Trusted End Node Security Tens On Vm For Mac

Good question. I'll answer it with an animation:When Host A sends the frame, the switch does not have anything in its MAC address table.

Upon receiving the frame, it records Host A's MAC Address to Switch Port mapping. Since it doesn't know where the destination MAC address is, it floods the frame out all ports.This assures that if host B exists (which at this point, the switch does not know yet), that it will receive it. Hopefully, upon receiving the frame, Host B will generate a response frame, which will allow the Switch to learn the MAC address mapping from the return frame.You can read more about how a Switch works (where I took the animation from). I would also suggest reading the entire article series for a closer look at.One last note regarding the terms Flooding vs Broadcast.

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A switch never broadcasts frames, a broadcast is not an action a switch can take. A switch can only flood a frame. A broadcast is simply a frame with a destination MAC address of ffff.ffff.ffff. This is often confused because the end effect is the same, but. The switch doesn't use ARP, but ARP can help in preventing this situation from occurring in the first place, for two reasons:.If node A is sending an IP packet to node B which isn't in its ARP cache, it will first send an ARP request (which is a broadcast packet, and will automatically be flooded to all ports by the switch). When node B sends its ARP reply, the switch will learn its MAC address. So, by the time actual data transfer happens, the switch already knows the MAC addresses of the participants, and doesn't need to flood data packets.Many devices, when their link goes up, will send a packet.

In addition to updating the ARP caches of other nodes on the network, the GARP will also fill the switch's MAC address table.IPv6 doesn't use ARP, but fulfills a similar purpose.So overall, although switches certainly will flood frames to unicast addresses they haven't learned, it's not necessary as often as you might think, because it will usually have the opportunity to learn nodes' addresses from broadcast frames beforehand. However, you can definitely observe it with a switch that's had its MAC table or that has just rebooted.

Questions:. if a VM is corrupted (hacked), what do I risk on others VMs running on the same physical machine?. What kind of security issues is there between VMs running on the same physical host?.

Is there (can you make) a list of those (potential) weaknesses and/or issues?Warning:I know many virtualization types/solutions exist, and may have different weaknesses. However, I'm mostly looking for general security issues about the virtualization techniques, rather than a particular vendor bug.Please provide real facts, (serious) studies, experienced issues or technical explanations. Do not (only) give your opinion. Examples:Two years ago, I've heard that there could be security issues related to the (accessing other machines main memory, I think), but I don't know if that is a practical threat as of today, or just a theoretical research subject.EDIT: I also found capable of retrieving GnuPG secret keys on the same physical machine, by exploiting the L3 CPU cache, even if GnuPG runs on another VM. GnuPG has been patched since. @MichaelHampton (and other +3000 rep) Sorry, I don't agree on closing this question. I'm not expecting, nor looking for debate to answer it, but only real facts, quoted studies, articles, or research papers, sharing experienced issues, technical explanations on isolation, etc.

What kind of debate do you think could arise?? I'm not asking if virtualization is 'good' or 'bad' for security, I asked precisely: 'what do I risk' and 'what security issues'! Feel free to edit my question if you think it could be more specific, but please don't ban it.–Apr 3 '13 at 22:33. Of course it is possible to exploit another VM running on the same hardware, given a working exploit.

Additionally, one can exist. Your question cites some recent work showing one. I'm not going to share any specific exploits or PoC here, but I'll gladly say how they can be made.The exploits that are used in this context are naturally different from ones that function when you're running on the same machine you are trying to exploit a service on, and they tend to be quite a bit harder due to the increased isolation.

However, some general approaches that can be used to accomplish such an exploit include:. Attack the hypervisor. If you can get a sufficiently privileged shell on the hypervisor given a VM, you can gain control over any VM on the system. The way to approach this is to look for data flows that exist from the VM into the hypervisor, and are highly hypervisor-dependant; things like paravirtualized drivers, clipboard sharing, display output, and network traffic tend to create this type of channel. For instance, a malicious call to a paravirtualized network device might lead to arbitrary code execution in the hypervisor context responsible for passing that traffic to the physical NIC driver. Attack the hardware on the host. Many devices allow for firmware updates, and if it happens to be possible to access the mechanism for that from a VM, you could upload new firmware that favours your intentions.

For instance, if you are permitted to update the firmware on the NIC, you could cause it to duplicate traffic bound for one MAC address (the victim's), but with another destination MAC address (yours). For this reason many hypervisors filter such commands where possible; ESXi filters CPU microcode updates when they originate from a VM.

Attack the host's architecture. The attack you cited, essentially yet another timing-based key disclosure attack, does this: it exploits the caching mechanism's impact on operation timing to discern the data being used by the victim VM in its operations. At the core of virtualization is the sharing of components; where a component is shared, the possibility of a side channel exists. To the extent that another VM on the same host is able to influence the behaviour of the hardware while running in the victim VM's context, the victim VM is controlled by the attacker. The referenced attack makes use of the VM's ability to control the behaviour of the CPU cache (essentially shared universal state) so that the victim's memory access times more accurately reveal the data it is accessing; wherever shared global state exists, the possibility of a disclosure exists also. To step into the hypothetical to give examples, imagine an attack which massages ESXi's VMFS and makes parts of virtual volumes reference the same physical disk addresses, or an attack which makes a memory ballooning system believe some memory can be shared when in fact it should be private (this is very similar to how use-after-free or double-allocation exploits work).

Consider a hypothetical CPU MSR (model-specific register) which the hypervisor ignores but allows access to; this could be used to pass data between VMs, breaking the isolation the hypervisor is supposed to provide. Consider also the possibility that compression is used so that duplicate components of virtual disks are stored only once - a (very difficult) side channel might exist in some configurations where an attacker can discern the contents of other virtual disks by writing to its own and observing what the hypervisor does. Of course a hypervisor is supposed to guard against this and the hypothetical examples would be critical security bugs, but sometimes these things slip through. Attack the other VM directly. If you have a proximal host to the victim VM, you may be able to take advantage of relaxed access control or intentional inter-VM communication depending on how the host is configured and what assumptions are made when deploying access control. 1999 kdx 220. This is only slightly relevant, but it does bear mention.Specific attacks will arise and be patched as time goes on, so it isn't ever valid to classify some particular mechanism as being exploitable, exploitable only in lab conditions, or unexploitable. As you can see, the attacks tend to be involved and difficult, but which ones are feasible at a particular time is something that changes rapidly, and you need to be prepared.That said, the vectors I've mentioned above (with the possible exception of the last one in certain cases of it) simply don't exist in bare-metal environments.

Edit: I thought this topic was done with months ago, but it has just been revived and now OP is asking for more 'real facts, quoted studies,' etc., so I figured what the heck.Exploits of this nature are:. Rare. Sensitive in nature and therefore not shared openly, and when they are, the exploits would be patched by the vendor before anyone on this site ever knew about them. Complicated and will vary by vendorWe can't say it's impossible to hack a hypervisor and gain access to other VMs.

The ever quotable of the OpenBSD project:You are absolutely deluded, if not stupid, if you think that aworldwide collection of software engineers who can't write operatingsystems or applications without security holes, can then turn aroundand suddenly write virtualization layers without security holes.A bit inflammatory but his point is well taken. In theory virtualization is supposed to provide complete isolation between the virtual machines and their host. In practice there are occasional security vulnerabilities that allow advanced attackers to circumnavigate these protections and gain access to other virtual machines or even worse their host (see ). As Ryan Ries mentions these kinds of vulnerabilities are pretty rare (which doesn't mean they aren't there) and often not disclosed by vendors but they do exist.If you are concerned about the potential for these kinds of attacks (and I think to some degree you should be) I recommend that you do not mix security zones on a single virtual host or virtual host cluster. For example - you would have a dedicated two host virtual host cluster for DMZ virtual machines, a dedicated cluster for middleware and a dedicated cluster for protected assets.

This way in the event that a vulnerability is exploited in such a way that allows an attacker to subvert other virtual machines or worse the hypervisor itself your security model is still intact.