Hi Everyone, It is critically important to note that the reported issue of session ID generation is NOT an issue in any version of Websphere Application Server 4.X. It has been reported that PQ47663V302 should be applied to Websphere Application Server V4.X. Please do not follow these directions. This patch is not supported on Websphere Application Server 4.X, hence any server with this patch is in an unsupported configuration. The issue is, however, a reasonably accurate description of a known and resolved issue in 3.X versions of Websphere Applicaton Server. PQ47663V302 is a resolution to this issue on any release of Websphere Application Server V3.02. There are versions of this patch available for 3.5.1, 3.5.2 and 3.5.3 as well. These fixes have been available since 5/1/2001. The site to obtain these from is http://www- 4.ibm.com/software/webservers/appserv/support.html . After applying the aforementioned patches to 3.02 or 3.5, the session generation algorithm is identical to that of Websphere Application Server V4.X. This algorithm is essentially totally random and is based on JCE which is widely recognized as one of the most sophisticated random ID generators. Also, we do not recommend relying on the session ID alone as a form of securing session data. If security is enabled and the accessed URLs are protected, the user must be authenticated to proceed. Websphere session and security code have been integrated such that each session access compares the authenticated user with the owner of the session. If these do not match, the session access is rejected with an UnauthorizedSessionRequestException. --Arun Kumar IBM WebSphere Service and Support. >Received: (qmail 29550 invoked from network); 20 Sep 2001 16:01:28 -0000 >Received: from outgoing2.securityfocus.com (HELO outgoing.securityfocus.com) (66.38.151.26) > by mail.securityfocus.com with SMTP; 20 Sep 2001 16:01:28 -0000 >Received: from lists.securityfocus.com (lists.securityfocus.com [66.38.151.19]) > by outgoing.securityfocus.com (Postfix) with QMQP > id 319048F2B9; Thu, 20 Sep 2001 09:55:05 -0600 (MDT) >Mailing-List: contact bugtraq- help@securityfocus.com; run by ezmlm >Precedence: bulk >List-Id: <bugtraq.list-id.securityfocus.com> >List-Post: <mailto:bugtraq@securityfocus.com> >List-Help: <mailto:bugtraq- help@securityfocus.com> >List-Unsubscribe: <mailto:bugtraq- unsubscribe@securityfocus.com> >List-Subscribe: <mailto:bugtraq- subscribe@securityfocus.com> >Delivered-To: mailing list bugtraq@securityfocus.com >Delivered-To: moderator for bugtraq@securityfocus.com >Received: (qmail 2797 invoked from network); 20 Sep 2001 11:14:28 -0000 >Message-ID: <98A3855A9087D411952F00508B61BD400268C688 @ZAJNBNT006> >From: "Dawes, Rogan (ZA - Johannesburg)" <rdawes@deloitte.co.za> >To: "'marc@suse.de'" <marc@suse.de>, bugtraq@securityfocus.com >Subject: RE: Websphere cookie/sessionid predictable >Date: Thu, 20 Sep 2001 13:13:37 +0200 >MIME-Version: 1.0 >X-Mailer: Internet Mail Service (5.5.2653.19) >Content-Type: text/plain; > charset="iso-8859-1" > >Hi, > >I did a similar analysis with an older version of WebSphere (3.2) for a >client, and have one comment to make that maybe you didn't pick up (or may >have been fixed in the interim): > >SessionID TIME >TWGYLZIAAACVDQ3UUSZQV2I 10:27:12 >TWGY0WYAAACVFQ3UUSZQV2I 10:27:13 >TWGZNZAAAACVHQ3UUSZQV2I 10:27:14 >TWG0BUYAAACVJQ3UUSZQV2I 10:27:15 >TWG0VIAAAACVLQ3UUSZQV2I 10:27:16 >TWG1ICIAAACVNQ3UUSZQV2I 10:27:17 >TWG111YAAACVPQ3UUSZQV2I 10:27:18 > yyy > >What I found was that the section marked "yyy" incremented by 2 for each >REQUEST made, not by time. So it is trivial to make a request every second, >making sure that the next number is only two from what your last number was. >If it was not, then someone ELSE has requested a session, and you should >begin brute forcing the interval between your previous and current >sessionids. The shorter the interval between requests, the smaller the space >to brute force, obviously. > >Perhaps someone can check if this patch also fixes that property of the >sessionid generation? > >Rogan > >-----Original Message----- >From: marc@suse.de [mailto:marc@suse.de] >Sent: 19 September 2001 07:44 >To: bugtraq@securityfocus.com >Subject: Websphere cookie/sessionid predictable > > >Hi folks, > >about three weeks ago, I discovered a hole in IBM's websphere 4.0 session ID >generation. Over a week ago, IBM made a fix for this available, so here is >the information about the vulnerability: > >(everybody who don't want to read about this vulnerability and just want to >know the patch info: install the eFix PQ47663V302) > >INTRO >websphere can generate sessionids which are put into cookies for users, to >be able to supply user tracking, e.g. user authenticates with userid and >password, and access to data is checked by checking if the sessionid is >authenticated or not. > > >THE BUG >during a security assessment for a bank, I collected several sessionids and >they did not look that random to me ... > >SessionID TIME >TWGYLZIAAACVDQ3UUSZQV2I 10:27:12 >TWGY0WYAAACVFQ3UUSZQV2I 10:27:13 >TWGZNZAAAACVHQ3UUSZQV2I 10:27:14 >TWG0BUYAAACVJQ3UUSZQV2I 10:27:15 >TWG0VIAAAACVLQ3UUSZQV2I 10:27:16 >TWG1ICIAAACVNQ3UUSZQV2I 10:27:17 >TWG111YAAACVPQ3UUSZQV2I 10:27:18 > xxxx y > >You can see that for seven requests, only 5 characters changed, and: >* the characters A-Z and 0-9 are used, hence 36 combinations possible per >char >* the sessionid is based on two counters which are counted up, the rest of > the string seems to be fixed. >* the first counter (xxxx) seems to count milliseconds (TWGxxxx), but > counts a bit too slow (see seconds 15 and 16, where both 1st rows of the > counters start with a 0). well, to cut a long story short, it is really > a counter which increases 65536 times per second and is then encoded to > the A-Z0-9 format. >* If you collect many sessionids (I collected 1000, it's obvious then), > you'll see that the the least signifcant char of the first counter are 95% > of the time showing a Y, I, A or Q. The reason for that is (my guess) that > the clock of the machine only can increase 7.500- 10.000 times instead of > 65536 because it's not a realtime clock and the server type is not a cray >:-) >* The second counter (y) is increasing by two every second. >The counters are in fact longer than 4, but this is the visible changes in >the example above. > >Then the guess was that the fixed strings may be based on the IP of the >client. So I checked with different IP addresses, but no difference in the >fixed strings of the sessionID. > > >THE RISK >If someone knows the time of the connect to the server (even with SSL >encrypted) an attacker can issue requests with changing sessionids until >it's the correct one. If an attacker just wants to have any user data, he >can constantly try some guessing. >As the first counter only has 7.500-10.000 values per second, and the >seconds counters just increases approx. once per second (or perhaps per >request), the sessionid can have 7.750 to 10.500 different values. >If a user is normaly connected for 15 minutes after authentication to an >eCommerce system (and does not forget to logout, otherwise the time is >extended by the session timeout). As an attacker is likely to succeed after >50% of the keyspace, he needs 3.875 to 5.250 attempts, so 4 to 5 requests >per second are enough. >Two customers were using the sessionids for the security of their eCommerce >system ... we are not talking about some weird feature nobody uses. >Short: it is an easy and likely attack. > > >THE FIX >install eFix PQ47663V302 and feel better > > >THANKS >to the IBM websphere team, which fixed the bug pretty fast for the customer. > > > >Greets, > Marc >-- > E@mail: marc@suse.de Function: Security Research and Advisory > PGP: "lynx -source http://www.suse.de/~marc/marc.pgp | pgp -fka" > Key fingerprint = B5 07 B6 4E 9C EF 27 EE 16 D9 70 D4 87 B5 63 6C >Private: http://www.suse.de/~marc SuSE: http://www.suse.de/security >
