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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2008.0473 -- [UNIX/Linux] rdesktop Multiple Vulnerabilities 8 May 2008 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: rdesktop Publisher: iDEFENSE Operating System: UNIX variants (UNIX, Linux, OSX) Impact: Execute Arbitrary Code/Commands Access: Remote/Unauthenticated CVE Names: CVE-2008-1801 CVE-2008-1802 CVE-2008-1803 Original Bulletin: http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=696 http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=697 http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=698 Comment: This advisory includes three (3) iDefense advisories regarding rdesktop. - --------------------------BEGIN INCLUDED TEXT-------------------- iDefense Security Advisory 05.07.08 http://labs.idefense.com/intelligence/vulnerabilities/ May 07, 2008 I. BACKGROUND rdesktop is an open source client that speaks the Remote Desktop Protocol (RDP). This allows Unix-based users to login to Windows Terminal Servers. More information is available at the following URL. http://www.rdesktop.org/ II. DESCRIPTION Remote exploitation of an integer underflow vulnerability in rdesktop, as included in various vendors' operating system distributions, allows attackers to execute arbitrary code with the privileges of the logged-in user. The vulnerability exists within the code responsible for reading in an RDP request. When reading a request, a 16-bit integer value that represents the number of bytes that follow is taken from the packet. This value is then decremented by 4, and used to calculate how many bytes to read into a heap buffer. The subtraction operation can underflow, which will then lead to the heap buffer being overflowed. III. ANALYSIS Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the logged in user. In order to exploit this vulnerability, an attacker must persuade a targeted user to connect to a malicious RDP server. IV. DETECTION iDefense confirmed the existence of this vulnerability in rdesktop version 1.5.0. Previous versions may also be affected. V. WORKAROUND iDefense is currently unaware of any effective workaround for this issue. VI. VENDOR RESPONSE The rdesktop maintainer has addressed this vulnerability with CVS revision 1.20 of iso.c. For more information, visit the following URL. http://rdesktop.cvs.sourceforge.net/rdesktop/rdesktop/iso.c?annotate=1.20&diff_format=h&pathrev=HEAD#l101 VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2008-1801 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems. VIII. DISCLOSURE TIMELINE 11/12/2007 Initial vendor notification 11/19/2007 Initial vendor response 05/07/2008 Public disclosure IX. CREDIT The discoverer of this vulnerability wishes to remain anonymous. Get paid for vulnerability research http://labs.idefense.com/methodology/vulnerability/vcp.php Free tools, research and upcoming events http://labs.idefense.com/ X. LEGAL NOTICES Copyright © 2008 iDefense, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customerservice@idefense.com for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information. iDefense Security Advisory 05.07.08 http://labs.idefense.com/intelligence/vulnerabilities/ May 07, 2008 I. BACKGROUND rdesktop is an open source client that speaks the Remote Desktop Protocol (RDP). This allows Unix-based users to login to Windows Terminal Servers. More information is available at the following URL. http://www.rdesktop.org/ II. DESCRIPTION Remote exploitation of a BSS overflow vulnerability in rdesktop, as included in various vendors' operating system distributions, allows attackers to execute arbitrary code with the privileges of the logged-in user. The vulnerability exists within the code responsible for reading in an RDP redirect request. This request is used to redirect an RDP connection from one server to another. When parsing the redirect request, the rdesktop client reads several 32-bit integers from the request packet. These integers are then used to control the number of bytes read into statically allocated buffers. This results in several buffers located in the BSS section being overflowed, which can lead to the execution of arbitrary code. III. ANALYSIS Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the logged in user. In order to exploit this vulnerability, an attacker must persuade a targeted user to connect to a malicious RDP server. IV. DETECTION iDefense confirmed the existence of this vulnerability in rdesktop version 1.5.0. Previous versions may also be affected. V. WORKAROUND iDefense is currently unaware of any effective workaround for this issue. VI. VENDOR RESPONSE The rdesktop maintainer has addressed this vulnerability with CVS revision 1.102 of rdp.c. For more information, visit the following URL. http://rdesktop.cvs.sourceforge.net/rdesktop/rdesktop/rdp.c?annotate=1.102&pathrev=HEAD#l1337 VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2008-1802 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems. VIII. DISCLOSURE TIMELINE 11/12/2007 Initial vendor notification 11/19/2007 Initial vendor response 05/07/2008 Public disclosure IX. CREDIT The discoverer of this vulnerability wishes to remain anonymous. Get paid for vulnerability research http://labs.idefense.com/methodology/vulnerability/vcp.php Free tools, research and upcoming events http://labs.idefense.com/ X. LEGAL NOTICES Copyright © 2008 iDefense, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customerservice@idefense.com for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information. iDefense Security Advisory 05.07.08 http://labs.idefense.com/intelligence/vulnerabilities/ May 07, 2008 I. BACKGROUND rdesktop is an open source client that speaks the Remote Desktop Protocol (RDP). This allows Unix-based users to login to Windows Terminal Servers. More information is available at the following URL. http://www.rdesktop.org/ II. DESCRIPTION Remote exploitation of an integer signedness vulnerability in rdesktop, as included in various vendors' operating system distributions, allows attackers to execute arbitrary code with the privileges of the logged-in user. The vulnerability exists within the code responsible for reallocating dynamic buffers. The rdesktop xrealloc() function uses a signed comparison to determine if the requested allocation size is less than 1. When this occurs, the function will incorrectly set the allocation size to be 1. This results in an improperly sized heap buffer being allocated, which can later be overflowed. III. ANALYSIS Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the logged in user. In order to exploit this vulnerability, an attacker must persuade a targeted user to connect to a malicious RDP server. IV. DETECTION iDefense confirmed the existence of this vulnerability in rdesktop version 1.5.0. Previous versions may also be affected. V. WORKAROUND iDefense is currently unaware of any effective workaround for this issue. VI. VENDOR RESPONSE The rdesktop maintainer has addressed this vulnerability with CVS revision 1.162 of rdesktop.c. For more information, visit the following URL. http://rdesktop.cvs.sourceforge.net/rdesktop/rdesktop/rdesktop.c?view=diff&pathrev=HEAD&r1=text&tr1=1.162&r2=text&tr2=1.118&diff_format=h#l1134 VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2008-1803 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems. VIII. DISCLOSURE TIMELINE 11/12/2007 Initial vendor notification 11/19/2007 Initial vendor response 05/07/2008 Public disclosure IX. CREDIT The discoverer of this vulnerability wishes to remain anonymous. Get paid for vulnerability research http://labs.idefense.com/methodology/vulnerability/vcp.php Free tools, research and upcoming events http://labs.idefense.com/ X. LEGAL NOTICES Copyright © 2008 iDefense, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customerservice@idefense.com for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBSCJ6bih9+71yA2DNAQJ0ywP/Wu8qqEjET3l63uAHEdUr5ylC5nfrqNOS 5LDjWHCS6JCctI/1uV0rdHJDdIPm802FvLxBJtR1KGLlFS2AhEKmN6UJDG1+uHeC yQEAy/tSqPvE6Jis9UsokniE6r4z5OvFavSNBRKulgLx1LWd0zndMYS3BxWVxSxS WLL/T/udg6c= =aghY -----END PGP SIGNATURE-----