Unicode Encoding Flaw Widespread

LordNikon writes "According to this CERT advisory: 'Full-width and half-width encoding is a technique for encoding Unicode characters. Various HTTP content scanning systems fail to properly scan full-width/half-width Unicode encoded HTTP traffic. By sending specially-crafted HTTP traffic to a vulnerable content scanning system, an attacker may be able to bypass that content scanning system.' A proof of concept affecting IIS is already being posted to security mailing lists. Cisco IPS and other IDS products are also affected." The CERT advisory lists 93 systems, with 6 reported as vulnerable (including 3com, Cisco, and Snort), 5 known not vulnerable (including Apple and HP), and the rest unknown.

Comments

Incident response

[Anonymous Coward]

I work incident response in a large web company (hence anonymous posting, natch) and currently we're treating this as "interesting, but case not proven". We test our web apps filter all input so I'm adding double-width unicode to our security regression test cases; however I'm happy to let the FD posters lab it out between them in the short term. These alleged IIS exploits don't work for us - which is not to say that we don't have some system, somewhere, for which this is an issue. At the end of the day it's just a clear restatement of something that's obvious to anyone - you need to filter input carefully, and you need to be aware of issues around alternative encodings. But it's not a "BRB" (big-red-button, ie emergency stop and all hands to the pumps to fix a vulnerability) issue for us - yet. The last time we had one of those, it was the Microsoft DNS server remote root... because most of our internal domain controllers were also running DNS servers.

Re:Hmmmm....

[peragrin]

1) unicode is better than having a hundred other encodes to debug
2)there's is nearly two billion chinese and Indians, who can't use your encoding.
3)I get just as much spam from US companies as I do foreign ones

Re:Depends on alphabet size

[rabtech]

IIRC, China was on its way to moving to an alphabet system (certain characters can be used for their alphabetic sounds in various circumstances) and so was Japan (look at Katakana/Hirigana).

It is likely that the introduction of the printing press (and later mass media like TV/radio and computers) have "arrested" this natural evolution. It may also be possible that the development of a national identity and cohesive society tends to put the brakes on some developments as well - if a single unified language is mandated by culture or a central authority then local variations are much less important.

Romanji (and to a certain extent English itself) is definitely influencing the Japanese; the younger generations even moreso. Japan may end up using an alphabet for day to day needs almost exclusively within the next 100 years. The situation in China is much less clear but it will probably happen eventually.

If we look into the past, nearly all societies with ideographic/logographic writing systems eventually moved to an alphabetic system. Hell, even Ancient Egyptian Hieroglyphs were partially syllabic much like Katakana. Much as previous posters have pointed out, changing to an alphabetic system from Chinese-characters has allowed Korea to dramatically raise literacy rates. There is only so much time for schooling and memorization, and only so much effort to expend on literacy. If a simpler writing system is more accessible then that is a net gain, even if there are a few things that logographic writing systems do better than alphabetic ones.