Saqib Ali asks: "I am a regular reader of Bruce Schneier's Blog, Articles, and Books, and I really like what he writes. However I recently read his book titled 'Secret and Lies' and I think he has done some in-justice to the security provided by the 'Code Signing.' On page 163 of his books, he (Bruce Schneier) basically states that: 'Code signing, as it is currently done, sucks.' Even though I think that Code Signing has its flaws, it does provide a fairly good mechanism for increasing security in an organization." What are your thoughts on the current methods of code signing in existence, today? If you feel like Bruce Schneier, how would you fix it? If you feel like Saqib Ali, what have you signed and how well has it worked?"The following are the reasons that he (Bruce Schneier) gives:
Bruce's Argument #1) Users have no idea how to decide if a particular signer is trusted or not.
My comments: True. However in an organization it is the job of the IT/security dept to make that determination. It shouldn't be left up to users. The IT dept should know not to trust "Snake Oil Corp.", however anything from "Citrix Corp" should be fairly safe. Moreover Windows XP SP2 provides provides a mechanism to create a Whitelist of certain trusted signers, and reject everything else. This is a very powerful security mechanism, and greatly increase the security in a corporate environment, if the workstations are properly configured. Having said that, this feature may not be that useful for home user, who can not tell the difference between Snake Oil and Citrix Corp.
Bruce's Argument #2) Just because a component is signed doesn't mean that it is safe.
My Comments: I fully agree with this. However Code Signing was never intended for this purpose. Code signing was design to prove the authenticity and integrity of the code. It was never designed to certify that the piece is also securely written.
Bruce's Argument #3) Just because two component are individually signed does not mean that using them together is safe; lots of accidental harmful interactions can be exploited.
My comment: Again Code Signing was was never designed to accomplish this.
Bruce's Argument #4) "safe" is not all-or-nothing thing; there are degrees of safety.
My comment: I agree with this statement.
Bruce's Argument #5) The fact that the evidence of attack (the signature on the code) is stored on the computer under attack is mostly useless: The attack could delete or modify the signature during the attack, or simple reformat the drive where the signature is stored.
My comments: I am not sure what this statement means. I think this type of attack is outside the realm of Code Signing. 'It is like saying host based IDs or anti-virus are useless, because if you can compromise the system you can turn them off.'
I would really appreciate any comments / thoughts / feedback on the above mentioned Bruce's arguments and my commentary. I am planning to give a short talk about benefits of code signing, so any feedback will really help me."