As others have pointed out, taint checking isn't confined to the code - the checking involves things like the run-time environment and when I say environment, I mean things like permissions on directories &/or files that your script accesses, having potentially unsafe directories on your path etc.

By way of explanation, there used to be a security hole on Solaris whereby /usr/bin was installed with permissions of 777 such that running a perl script (using -T) in which access was made to a binary e.g. ls, in the directory, then the script failed taint checking becuase the whole world & his uncle could potentially overwrite the accessed binary.

A subsequent security patch modified the permissions to 755 - at which point perls' taint checking found no problem with the use of the binary (tho' may have found problems elsewhere in the code;-).

For the case I have in mind, the system had both /usr/bin/ls & /bin/ls - where the permissions on /bin were 755 - changing the call from `ls` to `/bin/ls` provided an interim fix.

HTH ,

A user level that continues to overstate my experience :-))

In reply to Re: Doubt in perl taint by Bloodnok
in thread Doubt in perl taint by lakshmananindia

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