==================================================================== CERT-Renater Note d'Information No. 2018/VULN084 _____________________________________________________________________ DATE : 01/03/2018 HARDWARE PLATFORM(S): / OPERATING SYSTEM(S): Systems running ISC DHCP versions 4 prior to 4.1-ESV-R15-P1, 4.3.6-P1, 4.4.1. ===================================================================== https://kb.isc.org/article/AA-01565/75/CVE-2018-5732 https://kb.isc.org/article/AA-01567/75/CVE-2018-5733 _____________________________________________________________________ CVE-2018-5732: A specially constructed response from a malicious server can cause a buffer overflow in dhclient Author: Michael McNally Reference Number: AA-01565 Views: 786 Created: 2018-02-21 23:23 Last Updated: 2018-02-28 15:29 CVE: CVE-2018-5732 Document Version: 2.0 Posting date: 28 February 2018 Program Impacted: DHCP Versions affected: 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0 Severity: High Exploitable: Remotely Description: Failure to properly bounds check a buffer used for processing DHCP options allows a malicious server (or an entity masquerading as a server) to cause a buffer overflow (and resulting crash) in dhclient by sending a response containing a specially constructed options section. Impact: Affected versions of dhclient should crash due to an out-of-bounds memory access if they receive and process a triggering response packet. However, buffer overflow outcomes can vary by operating system and outcomes such as such as remote code execution may be possible in some circumstances. Where they are present, operating system mitigation strategies such as address space layout randomization (ASLR) should make it difficult to leverage this vulnerability to achieve remote code execution but we can not rule it out as impossible. The safest course is to patch dhclient so that the buffer overflow cannot occur. CVSS Score: 7.5 CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Workarounds: None. Active exploits: No known active exploits. Solution: Upgrade to the patched release most closely related to your current version of DHCP. DHCP 4.1-ESV-R15-P1 DHCP 4.3.6-P1 DHCP 4.4.1 Acknowledgements: ISC would like to thank Felix Wilhelm, Google Security Team, for reporting this vulnerability. Document Revision History: 1.0 Advance Notification 21 February 2018 1.1 Strengthened language in "Impact" section 27 February 2018 2.0 Public Disclosure 28 February 2018 If you'd like more information on ISC Subscription Support and Advance Security Notifications, please visit http://www.isc.org/support/. Do you still have questions? Questions regarding this advisory should go to security-officer@isc.org. To report a new issue, please encrypt your message using security-officer@isc.org's PGP key which can be found here: https://www.isc.org/downloads/software-support-policy/openpgp-key/. If you are unable to use encrypted email, you may also report new issues at: https://www.isc.org/community/report-bug/. Note: ISC patches only currently supported versions. When possible we indicate EOL versions affected. (For current information on which versions are actively supported, please see http://www.isc.org/downloads/). ISC Security Vulnerability Disclosure Policy: Details of our current security advisory policy and practice can be found here: https://kb.isc.org/article/AA-00861/164/ISC-Software-Defect-and-Security-Vulnerability-Disclosure-Policy.html This Knowledge Base article https://kb.isc.org/article/AA-01565 is the complete and official security advisory document. Legal Disclaimer: Internet Systems Consortium (ISC) is providing this notice on an "AS IS" basis. No warranty or guarantee of any kind is expressed in this notice and none should be implied. ISC expressly excludes and disclaims any warranties regarding this notice or materials referred to in this notice, including, without limitation, any implied warranty of merchantability, fitness for a particular purpose, absence of hidden defects, or of non-infringement. Your use or reliance on this notice or materials referred to in this notice is at your own risk. ISC may change this notice at any time. A stand-alone copy or paraphrase of the text of this document that omits the document URL is an uncontrolled copy. Uncontrolled copies may lack important information, be out of date, or contain factual errors. © 2001-2018 Internet Systems Consortium For assistance with problems and questions for which you have not been able to find an answer in our Knowledge Base, we recommend searching our community mailing list archives and/or posting your question there (you will need to register there first for your posts to be accepted). The bind-users and the dhcp-users lists particularly have a long-standing and active membership. ISC relies on the financial support of the community to fund the development of its open source software products. If you would like to support future product evolution and maintenance as well having peace of mind knowing that our team of experts are poised to provide you with individual technical assistance whenever you call upon them, then please consider our Professional Subscription Support services - details can be found on our main website. _____________________________________________________________________ CVE-2018-5733: A malicious client can overflow a reference counter in ISC dhcpd Author: Michael McNally Reference Number: AA-01567 Views: 634 Created: 2018-02-21 23:45 Last Updated: 2018-02-28 15:28 CVE: CVE-2018-5733 Document Version: 2.0 Posting date: 28 February 2018 Program Impacted: DHCP Versions affected: 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0 Severity: Medium Exploitable: Remotely Description: A malicious client which is allowed to send very large amounts of traffic (billions of packets) to a DHCP server can eventually overflow a 32-bit reference counter, potentially causing dhcpd to crash. Impact: Successful exploitation of this vulnerability may exhaust the memory available to dhcpd and/or cause it to crash, resulting in a denial of service to clients. CVSS Score: 5.9 CVSS Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Workarounds: None. Active exploits: No known active exploits. Solution: Upgrade to the patched release most closely related to your current version of DHCP. DHCP 4.1-ESV-R15-P1 DHCP 4.3.6-P1 DHCP 4.4.1 Acknowledgements: ISC would like to thank Felix Wilhelm, Google Security Team, for reporting this vulnerability. Document Revision History: 1.0 Advance Notification 21 February 2018 2.0 Public Disclosure 28 February 2018 If you'd like more information on ISC Subscription Support and Advance Security Notifications, please visit http://www.isc.org/support/. Do you still have questions? Questions regarding this advisory should go to security-officer@isc.org. To report a new issue, please encrypt your message using security-officer@isc.org's PGP key which can be found here: https://www.isc.org/downloads/software-support-policy/openpgp-key/. If you are unable to use encrypted email, you may also report new issues at: https://www.isc.org/community/report-bug/. Note: ISC patches only currently supported versions. When possible we indicate EOL versions affected. (For current information on which versions are actively supported, please see http://www.isc.org/downloads/). ISC Security Vulnerability Disclosure Policy: Details of our current security advisory policy and practice can be found here: https://kb.isc.org/article/AA-00861/164/ISC-Software-Defect-and-Security-Vulnerability-Disclosure-Policy.html This Knowledge Base article https://kb.isc.org/article/AA-01567 is the complete and official security advisory document. Legal Disclaimer: Internet Systems Consortium (ISC) is providing this notice on an "AS IS" basis. No warranty or guarantee of any kind is expressed in this notice and none should be implied. ISC expressly excludes and disclaims any warranties regarding this notice or materials referred to in this notice, including, without limitation, any implied warranty of merchantability, fitness for a particular purpose, absence of hidden defects, or of non-infringement. Your use or reliance on this notice or materials referred to in this notice is at your own risk. ISC may change this notice at any time. A stand-alone copy or paraphrase of the text of this document that omits the document URL is an uncontrolled copy. Uncontrolled copies may lack important information, be out of date, or contain factual errors. © 2001-2018 Internet Systems Consortium For assistance with problems and questions for which you have not been able to find an answer in our Knowledge Base, we recommend searching our community mailing list archives and/or posting your question there (you will need to register there first for your posts to be accepted). The bind-users and the dhcp-users lists particularly have a long-standing and active membership. ISC relies on the financial support of the community to fund the development of its open source software products. If you would like to support future product evolution and maintenance as well having peace of mind knowing that our team of experts are poised to provide you with individual technical assistance whenever you call upon them, then please consider our Professional Subscription Support services - details can be found on our main website. ========================================================== + CERT-RENATER | tel : 01-53-94-20-44 + + 23 - 25 Rue Daviel | fax : 01-53-94-20-41 + + 75013 Paris | email: cert@support.renater.fr + ==========================================================