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Re: Regular Expression Denial of Service
Thierry Zoller wrote:
With all due respect - this is known to be a vulnerability class since
over a century. Just because it doesn't have a acronym à la XSS
doesn't mean it's not known to be a vulnerability. Can we please stop
the attitude of inventing acronyms for vulnerabilites, making it look
like it's something new and funky.
It's the impact of something that makes it a vulnerability no the
Thierry, you are quite right. However, I don't think they claimed it was
a new class of vulnerabilities, and the responses since just added data
to it. So I think that while you are factually correct, you misread
their post. They shared their research with us.
GE> Alex Roichman wrote:
Checkmarx Research Lab presents a new attack vector on Web applications. By
exploiting the Regular Expression Denial of Service (ReDoS) vulnerability an
attacker can make a Web application unavailable to its intended users. ReDoS
is commonly known as a “bug” in systems, but Alex Roichman and Adar Weidman
from Checkmarx show how serious it is and how using this technique, various
applications can be “ReDoSed”. These include, among others, Server-side of
Web applications and Client-side Browsers. The art of attacking the Web by
ReDoS is by finding inputs which cannot be matched by Regexes and on these
Regexes a Regex-based Web systems get stuck.
For further reading:
GE> Alex, nice work. Thank you for sharing it with us.
GE> I'd recommend taking a look at Ilja van Sprundel's work with regular
GE> expression bugs in his Unusual bugs presentation.
GE> ... Where he played a bit with Google Code Search back in 2007, I think.
GE> He helped Google out by giving them his research, of course.
GE> I found two versions online:
GE> Ilja and I later discussed creating a real regex fuzzer to discover
GE> vulnerabilities, but I at least never had the time to play with it. He
GE> might have, I am CC:ing him.
GE> My best to Adar,
GE> Gadi Evron,