5 ms·
Scary, but not an RCE so threat is limited. It would mean malicious actors could possible create spoofed signatures on malware or possibly websites (EV certific
by AaronFriel 7y ago
Scary, but not an RCE so threat is limited. It would mean malicious actors could possible create spoofed signatures on malware or possibly websites (EV certificates?). Am I missing something or is there a way to turn a spoofed certificate into a single-click pwn? As I understand it, users would have to download a malicious payload or click a malicious URL to be exposed.
Edit: People are asking why I assume it's not an RCE. That's a good question, but I am assuming Krebs on Security wouldn't report an RCE as a potential certificate validation bug. This quote in particular:
> Equally concerning, a flaw in crypt32.dll might also be abused to spoof the digital signature tied to a specific piece of software.
If crypt32.dll has a memory bug that can be exploited by feeding it an ill-formed certificate, that is wormable and orders of magnitude more severe, not equally concerning.
We'll know more tomorrow, however.
- saagarjha 7y ago> Equally concerning, a flaw in crypt32.dll might also be abused to spoof the digital signature tied to a specific piece of software. Such a weakness could be exploited by attackers to make malware appear to be a benign program that was produced and signed by a legitimate software company. This looks like it could be abused to lead to code execution.
- resfirestar 7y agoWe’ll find out tomorrow. Even if it’s just spoofing a valid signature on a exe I’d still call that pretty serious. Might get a piece of malware masquerading as a legit background program past a lot of SOC analysts. I’d bet there’s more to it though.
- therein 7y agoAlso kernel modules.
- chrismarlow9 7y agoIf the matching of the signatures is bypassed because of the ability to manipulate the underlying control flow of the API via something like ROP, it could be used for many things. RCE in Windows Doesn't mean control over digital signature validation. But RCE in that particular API might mean both
- cjbprime 7y agoWait, how do you know it's not an RCE? Memory safety flaws in a DLL become RCE all the time. > is there a way to turn a spoofed certificate into a single-click pwn? e.g. The victim clicks on a link to go to your website, their machine wants to validate the TLS cert you sent it, it calls into crypt32.dll to do that, it corrupts memory while handling your attacking cert, pwn? We don't know enough (anything!) about the actual bug yet other than which DLL it's in.
- vsareto 7y agoI'm going to be disappointed if all of this hype is for non-code execution
- bob1029 7y agoThis would be a terrifying outcome if certificate-based RCE. Imagine an actor like google running an intentionally-compromised TLS certificate on their web servers... perhaps even targeted at specific IP addresses or on certain schedules to avoid detection. Certificates are an excellent initiation vector too. Especially, if one wanted to intentionally present a backdoor like this for national security reasons (all of the cryptographic primitives are already all right there for you to use to authenticate the cert).
- gpm 7y agoI'd more more worried about either hacked sites, or a country with something like China's Great Cannon doing that than a legitimate US company like Google. Google doing that would be a great way for everyone involved to spend a long time in jail.
- cjbprime 7y ago> Imagine an actor like google running an intentionally-compromised TLS certificate on their web servers... perhaps even targeted at specific IP addresses or on certain schedules to avoid detection. For what it's worth, you should read about Certificate Transparency, it tries to protect against this sort of problem. Browsers only accept certs that can prove they've been submitted to a public log, which means that their existence isn't being selectively exposed to some users only. (They mainly act as prevention against rogue certificate authorities rather than a rogue cert owner, though.)
- peterwwillis 7y ago> Am I missing something or is there a way to turn a spoofed certificate into a single-click pwn? 1) if there's a bug in the crypto library that creates RCE 2) if a mitm delivers a payload to an application (browser/plugin/etc) and that causes RCE. The former might cause NSA to get its panties in a wad. But it might be much worse than RCE. It might be like Heartbleed, where it can leak key material and memory all day (on servers and clients) and you'd never know it because the leak leaves no trace on the system and just looks like normal requests. Perfect exploit for spying. (And of course it's possible they had that exploit in their back pocket, but someone else reported it to M$, so now they're CYAing)
- atxlurker 7y agoThis is what I’m guessing
- DrJosiah 7y agoMy money is on it to disable support for sha1 in old products; maybe a bigger break than the prefix attack currently known.