- Little Snitch Disable Code Signing On Youtube
- Little Snitch Windows
- Little Snitch Disable Code Signing On Mac
- Little Snitch Mac
A security vulnerability was recently disclosed by Josh Pitts, a security researcher at Okta. This vulnerability affects third-party macOS apps that check the code signatures of other apps by tricking them into treating a maliciously crafted fat binary as coming from Apple. You can read all the details about this in Josh’s blog post.
Because this also affects Little Snitch, Josh contacted us back in April with all the information we needed and enough time to fix this before he disclosed the issue this week. We also disclosed this as CVE-2018-10470.
Little Snitch started to verify the code signatures of apps and processes that use network connections in version 4, released almost a year ago in July 2017. Little Snitch versions 4.0 to 4.0.6 are affected by this vulnerability and Little Snitch 4.1 released yesterday fixes this issue.
Jul 27, 2019 What’s New in Little Snitch 4.4. It is now compatible with macOS Catalina (10.15). Little Snitch now monitors access to Berkeley packet filtering devices. Also, it contains a new identity check for applications that are signed with the Mac Developer certificate that is currently corrected in Xcode. Simple interface modifications and bug fixes. Mar 09, 2020 In Little Snitch Connection alarm settings, you can now select the options to preset when a new connection alarm is displayed. You can now choose whether the rule created should take effect in the current profile or in all profiles. The detailed sections of Little Snitch now display code signing information for the login process. Jun 13, 2018 Little Snitch’s kernel extension sees that the rule requires a valid code signature by Apple. But the running process is based on the second slice of the fat binary and has no code signature. We call this a code signature mismatch. Little Snitch shows a connection alert that prominently notifies you about this mismatch.
Fortunately for us and our users, the consequences this has for Little Snitch are not as as bad as it first seems when reading the variousheadlinesaboutthisissue: What connections are allowed or denied by Little Snitch’s network filter is completely unaffected by this. The only thing that could happen is that Little Snitch would show inconsistent or incorrect information about an app’s code signature, but it would never actually allow connections that should not be allowed.
Jun 13, 2018 Little Snitch’s kernel extension sees that the rule requires a valid code signature by Apple. But the running process is based on the second slice of the fat binary and has no code signature. We call this a code signature mismatch. Little Snitch shows a connection alert that prominently notifies you about this mismatch. Jan 15, 2020 Code Signing Verification For added security, Little Snitch now monitors the code signatures of all programs wishing to be connected to the Internet. Appropriate Rules. Little Snitch 4.5 Crack Quickly find out why certain connections are allowed or denied. Enhanced Network Filters.
A Little More Detail
The issue discovered by Josh concerns fat binaries that contain code slices for multiple architectures (e.g. i386, x86_64, PowerPC) whereas the first architecture is signed correctly by Apple. When security tools would verify the code signature of such a fat binary, they would only check the first slice and assume that if that one is OK, the whole fat binary is OK. This means that they effectively ignore the code signature of all other slices, allowing attackers to put arbitrary code there.
What makes all this less of a problem for Little Snitch is that the actually relevant check happens in a kernel extension. Because the macOS kernel only knows about the code signatures of processes that are running, it only knows about the code signature of the correct slice. And since Little Snitch’s kernel extension uses this information to determine whether a running process has a valid code signature or not, it is completely unaffected by the issue discovered by Josh.
The parts of Little Snitch where this vulnerability manifests itself are Little Snitch Configuration, Network Monitor, and the connection alert. When these components try to verify the code signature of an app on disk, they will show incorrect information for the reasons outlined above. That’s bad, but still not as bad as you might think. Let’s play through what would happen here.
An Example
Little Snitch Disable Code Signing On Youtube
Let’s assume you have an universal app on your Mac that contains a maliciously crafted fat binary containing slices for two architectures. The first slice is signed by Apple and the second slice has no code signature. The second slice is being executed.
- You check the code signature of the app in Little Snitch Configuration and it incorrectly shows that the app is signed by Apple.
- You trust this incorrect information and create a rule that allows connections. This rule requires a valid code signature by Apple (unless you specifically opt-out of all code signature checks for that app).
- The app tries to connect.
- Little Snitch’s kernel extension sees that the rule requires a valid code signature by Apple. But the running process is based on the second slice of the fat binary and has no code signature. We call this a code signature mismatch.
- Little Snitch shows a connection alert that prominently notifies you about this mismatch. The default option in this alert is to deny any connection by the app.
The bottom line is that Little Snitch does not allow connections if you have a rule that requires a valid code signature, but the running process’ code signature does not match that.
It’s a bit different from the example above if you don’t have any rules for the app beforehand. Little Snitch will still show a connection alert for the maliciously crafted app and inform you with a big, yellow warning icon that the code signature of the running process is not valid.
In Conclusion
This issue shows once more that code signatures involve more complexity than just a cryptographic signature on a file. The code goes through many stages before it is actually executed by a CPU and the integrity of the signature must be preserved throughout all these stages. Little Snitch’s help chapter on code signature issues is a testimony to this.
In Little Snitch 4.0.5, a new feature was introduced:
This is a great idea, and I'm glad it was implemented, but I feel like there should be an option to turn it off. Personally, I use LS primarily to block network connections on untrusted networks until I can connect to a trusted VPN. As such, my 'trusted' profile allows all connections silently.
Little Snitch Windows
This new feature forces upon me the connection alert dialogs that I don't want while on a trusted network. Especially considering all the alerts for code signature mismatches are from commandline utilities that I trust.While I'm not privy to your codebase, I feel like having an option to disable that 'alert even in silent mode' behavior should be pretty easy to implement.