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at least once: CVE-2019-9195 Grin node (Rust) remote code execution vulnerability reported by

grin-forum.org/t/critical-vul fixed in 1.02

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May 13, 2019

My idea of remote code execution security is "Use Rust"; I would not be surprised if I screwed up once or twice. Looking forward to Philip Daian applying these new high standards to Emin "Sell your Bitcoin" Sirir. Or more importantly, his ridiculous Zcash claims. twitter.com/phildaian/stat…

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Well, at least it's not a memory corruption issue. Also love how archive directory traversal, which has been known for decades, suddenly has a funky name.

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Security best practices also don't just include using a memory safe language but also enforcing that nothing other than the update system can write to data that can be executed. A server process shouldn't be run with the privilege to modify itself or anything directly executable.

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There's a mistake in the design of the system beyond just a specific file write bug if the file write bug can trivially lead to code execution, similarly to how using a language where common mistakes become exploitable memory corruption bugs is not just about individual mistakes.

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in my experience path traversal -> code execution most of the time in practice

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It often does, but it doesn't when things are set up properly. The good old legacy *nix approach is having the application as a dedicated user not owning any of the code it uses or any data that it doesn't actually need to be able to write to at runtime. Also, enforcing noexec.

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It can be enforced through another layer like SELinux in a more precise way, but the fundamentals are just *nix security 101. For example, for good old Linux / Apache web servers, there's generally a www user (which can't write to base server code / data) and a www-data user too.

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So in a case like that, only root can update the packages with the base code / data, and the server runs as www, which can't write to /var/www/html with static data / code since it should be owned by www-data. This applies to everything though, whether it's an Android app, etc.

6:42 PM · May 13, 2019Twitter Web Client

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Android is moving towards removing execute / execute_no_trans from app_data_file and forcing apps to execute libraries/executables from the library directory (managed by the package manager) or directly mapping libraries from the apk. It's one of the things I implemented before.

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Of course, apps can still screw it up since there's more than native code execution, and fully preventing native code injection (removing execmem/execmod, ashmem execute, app_data_file execute) doesn't fix that. They can dynamically load data as code and pass to an interpreter.

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