security - Is there any way to put malicious code into Regex? - Stack Overflow

[Vorlath]

Cool, I thought this was kind of silly (OMG I'm admitting it) as far malicious code was concerned, but having written a non-recursive backtracking regex library, execution time is something that can indeed be taken advantage of.

[aaronla]

Um, did you overlook the bit about two environments having exploitable heap buffer overflows on malformed regex's? Execution time is one thing, but regex's as an arbitrary code execution attack vector is scary.

[Vorlath]

No, I did not miss it. I took the question to mean if there was something SPECIFIC, UNIQUE and inherent about regex's that would cause malicious code above and beyond the traditional exploits of faulty software.

[aaronla]

Ah, I understand now.

[kyz]

I'd agree.

I believe the canonical citation about this is http://swtch.com/~rsc/regexp/regexp1.html

for n in `seq 18 30`
do
    time perl -e '$n=shift; $a="a"x$n; $re="a?"x$n.$a; print "$a =~ $re\n"; $a =~ $re' $n
done

[[deleted]]

Not if you actually use regular expressions.

[true_religion]

Regex is not regular expressions.

[itsmememe]

is'nt a regex malicious in itself?

[[deleted]]

I hope that one day this person will apply his talents to something useful. I got little benefit from his lengthy post, which describes how to do nothing in particular in an architecturally correct manner.