3 ms·

Tcpdump is a unique codebase, has its own flaws/issues, and most certainly can be vulnerable, even if the overall stack is not. Run nothing as root, unless abs

by b112 4y ago

Tcpdump is a unique codebase, has its own flaws/issues, and most certainly can be vulnerable, even if the overall stack is not. Run nothing as root, unless absolutely required. And this had nothing to do with C or rust, running rust based software, any software as root, when not required,is unnecessary, and risky as well. Nothing is safe. Behave that way, or you do your oeg, and yourself, wrong. And its not OK to treat a dev env as fine to get compromised. Many orgs get borked by someone taking over dev machines, or infra, and sliding in that way.

lelanthran 4y ago
> Run nothing as root, unless absolutely required. Good advice, to be sure. Especially anything getting network input[1]. In a reddit thread once, I pointed out that there is no need for any server/service program to have any access to the file holding the startup configuration. There really isn't. If the user needs to write that configuration, use a different program with elevated privileges that do nothing but write that file. When the server starts up and needs to read config, it should start up as a user with elevated privileges, read the entire file in the first 3 lines of `main()`, then drop privileges and continue execution as normal. It will never be able to access that file during the rest of its execution. I don't think I've ever had a comment downvoted on reddit so hard! [1] No need to say "untrusted network input" - all input is untrusted unless you are literally in control of both parties.
- kqr 4y ago
  This would add complexity and in particular couple the application to a specific combination of operating system/privileges model/file system. How great is the benefit, really? How many things are exploited by the application writing to its own startup config?
  - lelanthran 4y ago
    > This would add complexity It would add fair bit of code, sure, but nicely isolated and not complex: It's three extra lines of code in the main function, and a separate utility to write the config. Balance that against the fact that the server then never writes its own config - that code is moved into the configuration-writing application, which removes complexity from the server application. > and in particular couple the application to a specific combination of operating system/privileges model/file system. It does indeed couple it to those systems that are sufficiently POSIX-like; however if you are writing a server that doesn't run on a Linux or BSD-derived system, you are out in the left field anyway. > How great is the benefit, really? How many things are exploited by the application writing to its own startup config? Well, the comment I made was in a thread discussing a vulnerability in the Microsoft Teams application[1] which was exploitable to retrieve the user's secrets[2] from their config file. So, that particular comment was very much on-topic and in-context. [1] Not sure if it was on all platforms or not. [2] Or something - I forget exactly what was leaked.
  - bawolff 4y ago
    most methods of getting persistence involve writing to some config file somewhere. Having your app not have rights to write to any sort of config or code files probably is fairly beneficial. How much is probably going to depends on how everything is configured, what your threat model is, what service it is, and a million other things.
- msm_ 4y ago
  Interesting idea, I quite like it. At the same time we have things like kubernetes, where most people store secrets in the environment variables that every single process in the container can read.
- peanball 4y ago
  This is what HAProxy does. At least the reading then dropping privileges. The admin writes the config themselves (or uses their own tool).
jeroenhd 4y ago
I think the point is that so what if you don't run these tools as root? If a malicious actor compromises your normal user account, they can also compromise your configuration files and alias sudo or set up a keylogger or do all kinds of nasty stuff. Going from standard user to root isn't much of a challenge for all but the most minimal infections in almost every standard setup for common Linux distributions. Malicious hackers don't need anything other than your current user permissions anyway; your API/ssh keys/crypto wallets are all stored in your home directory or other places a malicious program can get access to. There are exceptions, but I very much doubt that most people develop on QubesOS levels of Linux security. There is no practical antivirus software on Linux that will catch anyone sophisticated enough to exploit tcpdump. You need a LOT of know-how to run a "safe" Linux system that you're more likely to learn as a sysadmin than as a developer. Security is hard, especially on the Linux desktop, and it will be as long as attempts to add it are met with responses like "they're trying to take our freedom away". Common internet resources aren't much better ("just disable selinux") and current solutions for usability problems in this space (i.e. sandboxed applications not being able to access the directories you chose because they don't correspond to what the dev expected) aren't very great either. I definitely think we should use the resources for secure desktop computing that we do have, which includes running tshark and friends at the lowest level of privilege possible, but I can definitely understand why people ask "why should I bother" when most of their setup runs at Windows XP levels of security out of the box.
- bawolff 4y ago
  > Malicious hackers don't need anything other than your current user permissions anyway; your API/ssh keys/crypto wallets are all stored in your home directory or other places a malicious program can get access to. I mean, are you really running tcpdump on your local computer? I imagine you would be running it on the server you are trying to debug. So the security setup would plausibly be a bit different than that. But generally i agree. Good practise not to run things as root, especially this type of tooling, but its not exactly putting your private key into a public git repo level of insecurity by any means.
  - jeroenhd 4y ago

by b112 4y ago

lelanthran 4y ago

> Run nothing as root, unless absolutely required. Good advice, to be sure. Especially anything getting network input[1]. In a reddit thread once, I pointed out that there is no need for any server/service program to have any access to the file holding the startup configuration. There really isn't. If the user needs to write that configuration, use a different program with elevated privileges that do nothing but write that file. When the server starts up and needs to read config, it should start up as a user with elevated privileges, read the entire file in the first 3 lines of `main()`, then drop privileges and continue execution as normal. It will never be able to access that file during the rest of its execution. I don't think I've ever had a comment downvoted on reddit so hard! [1] No need to say "untrusted network input" - all input is untrusted unless you are literally in control of both parties.

kqr 4y ago
This would add complexity and in particular couple the application to a specific combination of operating system/privileges model/file system. How great is the benefit, really? How many things are exploited by the application writing to its own startup config?
- lelanthran 4y ago
  > This would add complexity It would add fair bit of code, sure, but nicely isolated and not complex: It's three extra lines of code in the main function, and a separate utility to write the config. Balance that against the fact that the server then never writes its own config - that code is moved into the configuration-writing application, which removes complexity from the server application. > and in particular couple the application to a specific combination of operating system/privileges model/file system. It does indeed couple it to those systems that are sufficiently POSIX-like; however if you are writing a server that doesn't run on a Linux or BSD-derived system, you are out in the left field anyway. > How great is the benefit, really? How many things are exploited by the application writing to its own startup config? Well, the comment I made was in a thread discussing a vulnerability in the Microsoft Teams application[1] which was exploitable to retrieve the user's secrets[2] from their config file. So, that particular comment was very much on-topic and in-context. [1] Not sure if it was on all platforms or not. [2] Or something - I forget exactly what was leaked.
- bawolff 4y ago
  most methods of getting persistence involve writing to some config file somewhere. Having your app not have rights to write to any sort of config or code files probably is fairly beneficial. How much is probably going to depends on how everything is configured, what your threat model is, what service it is, and a million other things.
msm_ 4y ago
Interesting idea, I quite like it. At the same time we have things like kubernetes, where most people store secrets in the environment variables that every single process in the container can read.
peanball 4y ago
This is what HAProxy does. At least the reading then dropping privileges. The admin writes the config themselves (or uses their own tool).

jeroenhd 4y ago

I think the point is that so what if you don't run these tools as root? If a malicious actor compromises your normal user account, they can also compromise your configuration files and alias sudo or set up a keylogger or do all kinds of nasty stuff. Going from standard user to root isn't much of a challenge for all but the most minimal infections in almost every standard setup for common Linux distributions. Malicious hackers don't need anything other than your current user permissions anyway; your API/ssh keys/crypto wallets are all stored in your home directory or other places a malicious program can get access to. There are exceptions, but I very much doubt that most people develop on QubesOS levels of Linux security. There is no practical antivirus software on Linux that will catch anyone sophisticated enough to exploit tcpdump. You need a LOT of know-how to run a "safe" Linux system that you're more likely to learn as a sysadmin than as a developer. Security is hard, especially on the Linux desktop, and it will be as long as attempts to add it are met with responses like "they're trying to take our freedom away". Common internet resources aren't much better ("just disable selinux") and current solutions for usability problems in this space (i.e. sandboxed applications not being able to access the directories you chose because they don't correspond to what the dev expected) aren't very great either. I definitely think we should use the resources for secure desktop computing that we do have, which includes running tshark and friends at the lowest level of privilege possible, but I can definitely understand why people ask "why should I bother" when most of their setup runs at Windows XP levels of security out of the box.

bawolff 4y ago
> Malicious hackers don't need anything other than your current user permissions anyway; your API/ssh keys/crypto wallets are all stored in your home directory or other places a malicious program can get access to. I mean, are you really running tcpdump on your local computer? I imagine you would be running it on the server you are trying to debug. So the security setup would plausibly be a bit different than that. But generally i agree. Good practise not to run things as root, especially this type of tooling, but its not exactly putting your private key into a public git repo level of insecurity by any means.
- jeroenhd 4y ago