From core.lists.bugtraq@CORE-SDI.COM Sun Nov 5 16:57:38 2000 From: "[iso-8859-1] Iván Arce" To: BUGTRAQ@SECURITYFOCUS.COM Date: Tue, 31 Oct 2000 19:57:34 -0300 Subject: [BUGTRAQ] [CORE SDI ADVISORY] Netscape servers heap buffer overflow [The following text is in the "iso-8859-1" character set] [Your display is set for the "US-ASCII" character set] [Some characters may be displayed incorrectly] CORE SDI http://www.core-sdi.com Vulnerability Report For Netscape Servers Heap Buffer Overflow Date Published: 2000-10-31 Advisory ID: CORE-2000103101 Bugtraq ID: 1865 CVE CAN: Non currently assigned. Title: Netscape Servers Heap Buffer Overflow Class: Boundary Condition Error (Buffer Overflow) Remotely Exploitable: Yes Locally Exploitable: Yes Release Mode: USER RELEASE Communications with the vendor have been remarkably difficult and to a large degree unproductive. Our last point of contact was October 18, 2000. This last communication stated that they would getting back to us shortly. Twelve days and several emails later we have decided to release without vendor support as it seems unlikely to be forthcoming. Vulnerability Description: An exploitable heap buffer overflow vulnerability was discovered in the Netscape Directory Server product. The Netscape Certificate Management System also has several server components that share the problem. Vulnerable systems allow the execution of arbitrary code as the user running the services. Vulnerable Packages/Systems: Netscape Certificate Management System 4.2 (Microsoft Windows NT 4.0 version) Netscape Directory Server 4.12 (Microsoft NT 4.0 version) Solution/Vendor Information/Workaround: Contact the vendor for a fix. Patches for iPlanet products are usually available from: http://www.iplanet.com/downloads/patches/index.html Additionally, advisories and information on security issues of these particular Netscape products can be obtained from: iPlanet Certificate Management System http://www.securityfocus.com/bid/1839 http://www.securityfocus.com/bid/676 Netscape Directory Server http://www.securityfocus.com/bid/1839 http://www.securityfocus.com/bid/676 Vendor notified on: October 2nd. 2000 Last contact with the vendor was on October 18th, 2000 when CORE SDI was informed that a patch for a problem reported previously was available and that information and a status report for the vulnerability described in this advisory would be available later that day. Since then no communication from the vendor was received, even after two emails asking for an update on October 23rd. and October 30th. Credits: This vulnerability was found by Emiliano Kargieman and Agustin Kato Azubel from Core SDI S.A. This advisory was drafted with the help of the SecurityFocus.com Vulnerability Help Team. For more information or assistance drafting advisories please mail vulnhelp@securityfocus.com. Technical Description - Exploit/Concept Code: The Netscape Directory Server 4.12 provides a Web to LDAP gateway, by means of the Directory Services Gateway (DSGW) web server. No authentication credentials are required from the client to access DSGW. The same service is installed and used as part of the Certificate Management System (Netscape/iPlanet CMS 4.2) and in this case it listens on a tcp port chosen during the installation process (24326/tcp in this example) A request with an URI as follows: http://server:24326/dsgw/bin/search?context=<1011 'a' chars> will overflow a buffer located in the heap. This buffer is allocated at 404501 with a call to an internal function that ends up calling MSVCRT!malloc. The buffer is allocated with a fixed size of 1024 bytes. Then at 40455B a call to sprintf is made like this: sprintf(pFixedBuffer, "%s$$LANGDIR/%s.conf", "../context/", userbuff); since sprintf doesn't do any bounds checking, the buffer can be overflowed depending on the size of 'userbuff' which is the argument the user specifies to the 'context=' parameter when calling the vulnerable program. A string of 999 bytes is enough to overflow the 'pFixedBuffer' by 1 byte and cause an exception. Due to the nature of the data overwritten, this vulnerability could be exploited, being possible to execute arbitrary machine code. The same problem seems to be present in almost all the binaries (12) in the Netscape\Server4\dsgw\bin directory (except for tutor). DISCLAIMER: The contents of this advisory are copyright (c) 2000 CORE SDI S.A. and may be distributed freely provided that no fee is charged for this distribution and proper credit is given. $Id: Netscape-Servers-advisory.txt,v 1.3 2000/10/31 22:47:47 iarce Exp $ --- "Understanding. A cerebral secretion that enables one having it to know a house from a horse by the roof on the house, It's nature and laws have been exhaustively expounded by Locke, who rode a house, and Kant, who lived in a horse." - Ambrose Bierce ==================[ CORE Seguridad de la Informacion S.A. ]========= Iván Arce Presidente PGP Fingerprint: C7A8 ED85 8D7B 9ADC 6836 B25D 207B E78E 2AD1 F65A email : iarce@core-sdi.com http://www.core-sdi.com Florida 141 2do cuerpo Piso 7 C1005AAG Buenos Aires, Argentina. Tel/Fax : +(54-11) 4331-5402 ===================================================================== --- For a personal reply use iarce@core-sdi.com