XSS with UTF-7 in Google

["HASEGAWA Yosuke" <yosuke.hasegawa () gmail com>]

XSS with UTF-7 in Google

XSS with UTF-7 was found in www.google.com (already fixed).
Although charset was specified in HTTP response header, but
charset-name was incorrect so XSS occurred.

PoC:
  http://www.google.com/search?hl=en&oe=cp932&q=%2BADw-script%2BAD4-alert(
  document.cookie)%2BADsAPA-/script%2BAD4-%2BACI-

The "cp932" is specified for output charset with "oe" parameter,
so responded HTTP header and <meta> in HTML from Google are like as:
--
Content-Type: text/html; charset=CP932
--
<meta http-equiv=content-type content="text/html; charset=CP932">
--

"cp932" is the similar name of the Shift_JIS encoding,
but it is not registered as correct charset name for IE.
IE recognizes only charset names hardocorded in MLang.dll
like as "Shift_JIS", "EUC-JP", "EUC-KR", "UTF-8" and so on.

Therefore, an automatic detection function for encoding works,
and detect as "UTF-7".

Typical incorrect charset name in japanese web pages are followings:

utf8 - Idiomatic expression of "UTF-8" hyphen falls out.
euc - Idiomatic expression of "EUC-JP"
jis - Idiomatic expression of "ISO-2022-JP"
MS932 / MS932 / CP942C - Comparable encodings to Shift_JIS on Java
Windows-31J - IANA registered name for Codepage 932, but not
registered in Windows.

Status:
Apr 17 2007
 Reported to Google via IPA/ISEC <http://www.ipa.go.jp/security/index-e.html>
Dec 26 2007
 Received reply it fixed from Google via IPA/ISEC.

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