[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date: Tue, 14 Jul 2009 22:00:18 +0200
From: Florian Weimer <fw@...eb.enyo.de>
To: oss-security@...ts.openwall.com
Subject: Fixing the XML signature HMAC truncation authentication bypass
Quoting from <http://www.kb.cert.org/vuls/id/466161>:
| XML Signature Syntax and Processing (XMLDsig) is a W3C
| recommendation for providing integrity, message authentication,
| and/or signer authentication services for data. XMLDsig is commonly
| used by web services such as SOAP. The XMLDsig recommendation
| includes support for HMAC truncation, as specified in RFC2014. When
| HMAC truncation is under the control of an attacker, however, this
| can result in an effective authentication bypass. For example, by
| specifying an HMACOutputLength of 1, only one bit of the signature
| is verified. This can allow an attacker to forge an XML signature
| that will be accepted as valid.
What shall we do about this? Shall we just cap the value at 80 or 96
bits in our implementations?
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
