5 ms·

Those two pieces of advice really are like telling programmers "just don't make mistakes". Giving that advise is really, really easy. Every competent web devel

by Xk 16y ago

Those two pieces of advice really are like telling programmers "just don't make mistakes". Giving that advise is really, really easy. Every competent web developer knows that. The hard part is actually implementing it. For example, lots of programs written today still have buffer overflow vulnerabilities. Those are even older. The fix is also very simple: "Check the bounds of your arrays before you use them". That is, again, just telling the developer to not make mistakes. Designing security into your app can help with preventing XSS attacks, but there is no single perfect way.

mcorrientes 16y ago
that's true but especially code hosting sites, should be a bit more concerned. Using a WAF and white listing parameters, may be a good start too. Just another reason why I keep the code internal.
- Xk 16y ago
  > especially code hosting sites, should be a bit more concerned. Not really. There are many examples of sites which should be more concerned. Anything with your credit card information, say. > Using a WAF and white listing parameters Yeah, that's a good start. But you need to make sure everything goes through the white list, and that's the hard part. > Just another reason why I keep the code internal. What does this have to do with security?
- d1b 16y ago
  I think in the github and launchpad case the security that a WAF normally offers would have been broken because the data to trigger the vector did not come through http nor https. I suggest you have a play around with github wiki's they already have 'html sanitization' built in.
nupark 16y ago
For example, lots of programs written today still have buffer overflow vulnerabilities. Those are even older. The fix is also very simple: "Check the bounds of your arrays before you use them". That is, again, just telling the developer to not make mistakes. Actually, the fix isn't to stop making mistakes. The fix is to stop using APIs and/or runtimes that make it easy to make mistakes. Design your APIs such that buffer overflows aren't possible. The same thing applies to web development and escaping of output data. In a proper API, it should literally not be possible to accidentally write unescaped data to the page.
- Xk 16y ago
  > Actually, the fix isn't to stop making mistakes. I know that. I wrote "The fix is also very simple: "Check the bounds of your arrays before you use them"" in order to demonstrate that saying "Sanitize your input" is equally wrong.
  - nupark 16y ago
    The fix IS that simple. Stop using non-sanitizing APIs. Your equated that with saying "stop making mistakes," which is what I objected to. The original poster was right: people need to simply stop using frameworks that do not sanitize their data by default.
    - Xk 16y ago
      All you've done now is shipped off the responsibility to the API. The API is not bug free, I guarantee you. There will still be XSS vulnerabilities, but they'll just live in the API now. Imagine you decide to fix buffer overflows by switching from C to Java. You're no longer relying on the fact that your code won't have buffer overflows, you're relying on the fact that (1) the JVM code doesn't have buffer overflows and (2) the JVM will catch all your buffer overflows and throw exceptions. I feel very confident Java has few, if any, bugs. I do not, however, hold that same level of confidence with most APIs in use today. They simply haven't had the time to become as robust. However, even then, this does not solve all of your issues. There are times when you need to insert tags dynamically, and once you start doing that, there are a million more ways things can go wrong. Sure, you can put another restrictive API in front of that which requires the programmer to take ten lines to describe the single tag she wants, but those APIs will rarely get used because of this. At the end, for any class of vulnerabilities, there is always a way to entirely eliminate it. Rarely is it the case, however, that you can do so without dramatic losses in other areas.
      - nupark 16y ago
        I honestly have no idea what you're talking about or advocating, if anything. If you switch to the JVM, a buffer overflow triggers determinate behavior -- it throws an exception rather than writing over the saved return address or the heap. The attack surface is by it's nature is much smaller than if you rely on programmer correctness in C. As for inserting tags "dynamically," this sounds like a broken templating system if that means exposing the programmer to fail-fast (instead of fail-safe) escaping APIs.

by Xk 16y ago

mcorrientes 16y ago

that's true but especially code hosting sites, should be a bit more concerned. Using a WAF and white listing parameters, may be a good start too. Just another reason why I keep the code internal.

Xk 16y ago
> especially code hosting sites, should be a bit more concerned. Not really. There are many examples of sites which should be more concerned. Anything with your credit card information, say. > Using a WAF and white listing parameters Yeah, that's a good start. But you need to make sure everything goes through the white list, and that's the hard part. > Just another reason why I keep the code internal. What does this have to do with security?
d1b 16y ago
I think in the github and launchpad case the security that a WAF normally offers would have been broken because the data to trigger the vector did not come through http nor https. I suggest you have a play around with github wiki's they already have 'html sanitization' built in.

nupark 16y ago

For example, lots of programs written today still have buffer overflow vulnerabilities. Those are even older. The fix is also very simple: "Check the bounds of your arrays before you use them". That is, again, just telling the developer to not make mistakes. Actually, the fix isn't to stop making mistakes. The fix is to stop using APIs and/or runtimes that make it easy to make mistakes. Design your APIs such that buffer overflows aren't possible. The same thing applies to web development and escaping of output data. In a proper API, it should literally not be possible to accidentally write unescaped data to the page.

Xk 16y ago
> Actually, the fix isn't to stop making mistakes. I know that. I wrote "The fix is also very simple: "Check the bounds of your arrays before you use them"" in order to demonstrate that saying "Sanitize your input" is equally wrong.
- nupark 16y ago
  The fix IS that simple. Stop using non-sanitizing APIs. Your equated that with saying "stop making mistakes," which is what I objected to. The original poster was right: people need to simply stop using frameworks that do not sanitize their data by default.
  - Xk 16y ago
    All you've done now is shipped off the responsibility to the API. The API is not bug free, I guarantee you. There will still be XSS vulnerabilities, but they'll just live in the API now. Imagine you decide to fix buffer overflows by switching from C to Java. You're no longer relying on the fact that your code won't have buffer overflows, you're relying on the fact that (1) the JVM code doesn't have buffer overflows and (2) the JVM will catch all your buffer overflows and throw exceptions. I feel very confident Java has few, if any, bugs. I do not, however, hold that same level of confidence with most APIs in use today. They simply haven't had the time to become as robust. However, even then, this does not solve all of your issues. There are times when you need to insert tags dynamically, and once you start doing that, there are a million more ways things can go wrong. Sure, you can put another restrictive API in front of that which requires the programmer to take ten lines to describe the single tag she wants, but those APIs will rarely get used because of this. At the end, for any class of vulnerabilities, there is always a way to entirely eliminate it. Rarely is it the case, however, that you can do so without dramatic losses in other areas.
    - nupark 16y ago
      I honestly have no idea what you're talking about or advocating, if anything. If you switch to the JVM, a buffer overflow triggers determinate behavior -- it throws an exception rather than writing over the saved return address or the heap. The attack surface is by it's nature is much smaller than if you rely on programmer correctness in C. As for inserting tags "dynamically," this sounds like a broken templating system if that means exposing the programmer to fail-fast (instead of fail-safe) escaping APIs.