On Wednesday this week, virtualisation behemoth VMWare published a security advisory describing two just-patched security holes in its products.
Virtualisation in general, and VMWare’s product set in particular, is widely used to turn individual physical computers into several “virtual computers” that share the same physical hardware.
These virtual computers, known in the jargon as VMs (short for virtual machines), realistically pretend to be independent computers in their own right, each one booting and running an operating system of its own, as a physical computer would.
This means that one physical server, located in an on-site server room or in a cloud data centre, can flexibly be divvied up amongst multiple different users, who could come from separate departments in one organisation, or even from different companies.
Each user gets access to what looks like, feels like, and runs like a computer of all their own, with an operating system and application stack of their own choice.
Each VM, known in the jargon as a guest, has its own virtual hard disks, stored as a regular files on the physical server, known as the host.
This means you can not only divide up one physical disk array into a variety of differently-sized guest disks, to suit the varying needs of the various guest users, but also easily snapshot and archive entire VMs by copying their virtual disk files.
You can even clone an existing VM, and migrate the files that store its content to another physical server, in order to adapt quickly to rising demand for service or to recover from regional outages.
Risks and challenges
As you can imagine, however, this flexibility comes with some significant risks and challenges.
Firstly, the virtualisation software needs to stop guest VMs on the same physical computer from interfering with each other (or, worse, from interfering with the host operating system itself), given that they all share and compete for the same physical RAM and peripherals.
Secondly, given that some networks may have tens of thousands of VMs or more running in data centres across the world at ay moment, the control software that manages this ocean of VMs needs to be especially resilient against attack by unauthorised users.
Ransomware crooks, in particular, love to get access to VM control panels, not least because:
- If they can inject their malware into thousands of VMs in one go, they can scramble all your VMs “from inside” at the same time, possibly with one button-click from a central console.
- If they can simultaneously halt all the VMs on a physical server, then the VM virtual disk files in the host operating system will no longer be locked for use by the virtualisation software, so any ransomware launched on the host will simply scramble the virtual disks along with everything else.
Indeed, when the infamous REvil ransomware crime gang put up $1,000,000 in Bitcoin in 2020 as an enticement to attract new network hacking “affiliates” to its underworld business, knowledge of Hyper-V (Microsoft’s virtualisation software) was explicitly listed amonst the necessary “experience and skills”.
Other necessary skills for a “job” with REvil, in case you’re wondering, included experience with backup devices such as NAS and tape, representing another part of your network infrastructure that ransomware criminals like to attack before they launch their file-scrambling denouement. With your VMs disrupted along with all your regular computers, the attackers aim to increase the extent to which they derail your business. With your backups disrupted, ransomware attackers aim to decrease your ability to recover on your own, so that they can squeeze you harder with their blackmail demands for decrypting your scrambled files.
The latest bugs
The latest VMware updates close off two security vulnerabilities in the VM control and management tools that the company provides:
- CVE-2022-22972. Authentication bypass. Products affected: VMware Workspace ONE Access, Identity Manager and vRealize Automation.
A cybercriminal who already had a foothold on your network, even if they were only a regular user with limited security entitlements, could launch and access the above management tools as an adminstrative user. Although this wouldn’t give the attacker sysadmin equivalence on the physical network, it could put them instantly in charge of your entire fleet of virtual servers.
- CVE-2022-22973. Elevation of Privilege (EoP). Products affected: VMware Workspace ONE Access and Identity Manager.
While the first bug means that an invader could level up to your own sysadmins inside the VM management tools, this bug means that the invader could abuse the VM tools to level up to your sysadmins on the computer where they have their foothold.
Ironically, therefore, these VMware security holes could be combined to give an intruder a leg-up to both physical and virtual root-level powers at the same time.
What the government says
Note that neither of these bugs can be abused from outside your network for what’s known as RCE, short for remote code execution.
As the name suggests, RCE bugs are especially dangerous because they often provide a way for criminals to inject malware into your network in the first place, as the launching point for an intrusion.
Nevertheless, the US government thinks that CVE-2022-22972 and CVE-2022-22973 are sufficiently serious, given their potential for abuse by attackers, that it has issued Emergency Directive 22-03: Mitigate VMware Vulnerabilities.
This document doesn’t just talk about the risks, as we have above, or advise government agencies to get busy with their patching.
If you strip out the offialese and the bureaucratic boilerplace from this Directive, you are left with these very simple but uncompromising instructions:
- FIND all unpatched copies of all affected products on your network;
- PATCH them if you can, without delay, or
- REMOVE them from the network at once if you can’t patch, and do it
- NOW (deadline 2022-05-23T20:59Z, i.e. before 5pm EDT/2pm PDT next Monday).
- REPORT what you did to comply with the first 3 steps (deadline 2022-05-24T15:59Z, i.e. before noon EDT/9am PDT next Tuesday).
In three words: discover, remediate, report.
Or, as we like to say on Naked Security: Don’t delay – do it today!
Not enough time or staff? Learn more about Sophos Managed Threat Response:
Sophos MTR – Expert Led Response ▶
24/7 threat hunting, detection, and response ▶