Document ID: 59667
Last Updated 2003 May 22
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Original Report: http://www.ntbugtraq.com/default.asp?pid=36&sid=1&A2=ind0305&L=ntbugtraq&F=P&S=&P=6219 . Cisco responded with the following, which is also archived at http://www.ntbugtraq.com/default.asp?pid=36&sid=1&A2=ind0305&L=ntbugtraq&F=P&S=&P=6392 .
To: NTBugTraq Subject: Re: Cisco VPN Client can be used to gain local administrator rights (All Versions, patched or otherwise) Date: Thu, 22 May 2003 19:30:37 -0700 Author: Sharad Ahlawat <email@example.com> In-Reply-To: <78C391165E0FA34090C8794E6BEB7286136201:nospam.ffeplw2exmb01.ffe.foxeg.com> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 This is in response to the mail sent by Nick Staff. The original mail is available at default.asp?pid=36&sid=1&A2=ind0305&L=ntbugtraq&F=P&S=&P=6219 Physical access to the workstation and a valid user account are required to exploit this vulnerability which results in a person gaining local system administrative privileges. This vulnerability does not compromise the confidentiality of the data traversing the VPN tunnel established by the Cisco VPN Client. Upon initial confirmation of the vulnerability, Cisco bug CSCeb12179 was opened to address the issue. Cisco continues to work on its resolution with due urgency and will announce an updated version to its customers as soon as one is tested and available. The current workaround/mitigation technique is to make all the Cisco VPN client executable files read only for non administrative user groups. Cisco confirmed the report of this new vulnerability on May 15, 2003 and had requested joint disclosure with the reporter once a fix was tested and available for our customers. Cisco will continue to follow the guidelines of responsible disclosure with any reported vulnerabilities in its products. We welcome your reports and comments at psirt:nospam.cisco.com. For further information, please visit our web site at http://www.cisco.com/go/psirt . /Sharad On Thursday 22 May 2003 11:54, Nick Staff wrote: NS>First, before getting into this exploit I think it's only fair to say NS>that my last post, "Cisco Systems VPN Client allows local logon with NS>Elevated Privileges" was as Cisco's representative Sharad Ahlawat said, NS>outdated and already addressed (see following link): NS> NS>http://www.cisco.com/warp/public/707/vpnclient-multiple2-vuln-pub.shtml NS> NS>That said, I was sufficiently enough embarrassed to see if I could get NS>around their patched client, and here's how to do it: NS> NS>- Log on as a standard user. NS>- Browse to the C:\winnt directory, right click on explorer.exe and NS>choose copy. NS>- Browse to C:\Program Files\Cisco Systems\VPN Client (the directory NS>with ipsecdialer.exe) and paste a copy of explorer.exe into the folder. NS>- Double click on ipsecdialer.exe and select options > Windows logon NS>properties. NS>- Click on the first box to "enable start before log on". NS>- Click OK and Close. NS>- Rename ipsecdialer.exe to ipsecdialer.ex_ NS>- Rename the copy of explorer.exe to ipsecdialer.exe NS>- Close any open windows. NS>- log out. NS>- log back on as the same standard user. NS>- Click okay on any error messages that appear. NS>- DO NOT CLOSE THE EXPLORER WINDOW THAT IS OPEN. NS>- At this point you may see your desktop or you may not (have had it NS>happen both ways), but whatever the case, that Explorer window is open NS>as local system and anything else you see is opened as the standard NS>user. NS>- In the open explorer window press the Up folder icon until you get to NS>My computer. NS>- Double click on Control Panel, then Administrative Tools, then NS>Computer Management NS>- Expand Local Users and Groups and add your Standard User account to NS>the Local Administrators Group. NS> NS>The following steps are provided to return your machine to it's previous NS>state (i.e. logging in without the client launching explorer) NS> NS>- Navigate to C:\Program Files\Cisco Systems\VPN Client and open the NS>vpnclient.ini file NS>- set runatlogon=0 NS>- Save the file and restart the machine (Ctrl-Alt-Del if no Start NS>button) NS> NS> NS>And to Verify the Changes took... NS> NS>Log on as the Standard user and do whatever you want. NS> NS>Cisco has been notified about this issue and has acknowledged it, but NS>since asking for a week to test it further I have not heard from them NS>again. NS> NS>Possible Issue/Workaround NS> NS>I can't code, but it would seem the file at fault is csgina.dll which is NS>Cisco's replacement Gina that's installed automatically (and I assume is NS>what allows the explorer window to be launched in the system process). NS>Also, this exploit would be harder if not impossible were Cisco to NS>secure their install folder, but unfortunately even if I have NS>permissions set on the Program Files folder to only allow Users Read NS>access the Cisco install creates a subfolder which grants the NS>Interactive user Modify permissions. I think they do this because the NS>program constantly re-encrypts the group authentication key which is NS>stored in a text file in that directory. NS> NS>This has been Verified on Windows 2000 with SP3 and Windows 2003 Server NS>with the newest version of the Cisco VPN client (as well as older NS>versions too). NS> NS>Thanks, NS> NS>Nick Staff NS> NS> - -- Sharad Ahlawat Cisco Product Security Incident Response Team (PSIRT) http://www.cisco.com/go/psirt Phone:+1 (408) 527-6087 PGP-key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xC12A996C -----BEGIN PGP SIGNATURE----- Comment: PGP Signed by Sharad Ahlawat iD8DBQE+zYfNGoGomMEqmWwRAnDBAKDTFL+75YhfAx87g8LkiVmbTlWc1ACfeyWN 9NIwGdso0VlaezbupA6j5XU= =2pCG -----END PGP SIGNATURE-----
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|Updated: Oct 08, 2004||Document ID: 59667|