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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2020.2339 Citrix Hypervisor Security Update 9 July 2020 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Citrix Hypervisor Citrix XenServer Publisher: Citrix Operating System: Virtualisation Citrix XenServer Impact/Access: Increased Privileges -- Existing Account Denial of Service -- Existing Account Provide Misleading Information -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2020-15565 CVE-2020-15563 Reference: ESB-2020.2320 Original Bulletin: https://support.citrix.com/article/CTX277456 - --------------------------BEGIN INCLUDED TEXT-------------------- Citrix Hypervisor Security Update Reference: CTX277456 Category : Medium Created : 08 Jul 2020 Modified : 08 Jul 2020 Applicable Products o Citrix Hypervisor o XenServer Description of Problem Two issues have been identified in Citrix Hypervisor that may, if exploited, allow privileged code in an HVM guest VM to compromise or crash the host. These issues only apply in specific configurations; furthermore, Citrix believes that there would be significant difficulty in successfully executing these specific attacks. CVE-2020-15565: insufficient cache write-back under VT-d This issue may allow the administrator of an HVM guest VM to compromise the host. This issue is only applicable to hosts where the host administrator has explicitly assigned a PCI-passthrough device to the attacking VM. Hosts with AMD CPUs are not affected. Hosts where Hardware Assisted Paging (HAP) has been disabled for the attacking VM, or where the host CPU does not support HAP, are not affected. CVE-2020-15563: inverted code paths in x86 dirty VRAM tracking This issue may allow the administrator of an HVM guest VM to crash the host. This issue is only applicable to hosts that do not have HAP (or deployments where the host administrator has explicitly enabled shadow paging for the attacking VM). Furthermore, the console of the attacking VM must be being actively consumed e.g. by monitoring it from XenCenter. CVE-2020-15565 affects all supported releases of Citrix Hypervisor, up to and including Citrix hypervisor 8.2 LTSR. CVE-2020-15563 affects Citrix Hypervisor 8.2 LTSR, Citrix Hypervisor 8.1 and Citrix Hypervisor 8.0. Mitigating Factors See the per-issue descriptions above. Note in particular that customers who have not assigned PCI passthrough devices to untrustworthy guests and are using hosts with HAP support and have not explicitly enabled shadow paging are not at risk from these issues. Most recent CPUs have HAP support (known as EPT on Intel systems). What Customers Should Do Hotfixes have been released to address these issues. Citrix recommends that affected customers install these hotfixes as soon as their patching schedule permits. The hotfixes can be downloaded from the following locations: Citrix Hypervisor 8.2 LTSR: CTX277444 - https://support.citrix.com/article/ CTX277444 Citrix Hypervisor 8.1: CTX277443 - https://support.citrix.com/article/CTX277443 Citrix Hypervisor 8.0: CTX277442 - https://support.citrix.com/article/CTX277442 Citrix XenServer 7.1 LTSR CU2: CTX277441 - https://support.citrix.com/article/ CTX277441 Citrix XenServer 7.0: CTX277440 - https://support.citrix.com/article/CTX277440 Changelog +--------------------------+--------------------------------------------------+ |Date |Change | +--------------------------+--------------------------------------------------+ |2020-07-08 |Initial Publication | +--------------------------+--------------------------------------------------+ - --------------------------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. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== 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 iQIVAwUBXwZ3leNLKJtyKPYoAQhr+w/+MAjqbBhovIV6GGhSlaIDcpvgUBOU4pkr xdGIgPO11k8YwIyyHizbTuVvR7O5cchQWUxbNZGfITZ94pQKoK3dKk3KarzbLscI QJZnwfBiPlDfAqnOgnLEywo/8VMwEdb2J9ZACV4xlRigEUXIDaMOZZzYHkYBmniY 6BJkPKKNsRWuvu1pkGRnaGwFZuqDmR+tPBGQ4ZxMGpEF60vYkBYBWyL6UNeCuEGY 5yxBnMBS2s3DOamvSnGfHoyAAAIzZOMkcCVai9zsqD+ow8VOUX5qXbcVU6/qWadv S3kkUOSvpf9w8M8gajudfCi2kkGbugEXgOjt2rCWKdYvJNrqQcw5FOBIf7fmGh5F L7FHTwDxnT0mKrD8BX61Z2+0sw4S8Xrfn6zSRIODjbgjpvXq6wzNSoU/w1+w3K5P eSR9bR5t8guPVMCIa6d7A5YrcpRS49x/EjD5Co/BR1ehyrSQ2iAtJ899YTUN3iB9 h3TQ9tZ1U/M7no9PWc+6gEYspAvvswGMi6RbldadihONC47YTXcHduXJt9oauowh 2YNRlf42/cg9qSMOKTyF7DYRB4WEs8oWEkV9y6DSOb7VQMSuJmpHgxNXjysonf6S 5KawnPZ1qex0ms6aJPyq0wqfAVmwf9AwgcRmVBUeIzepN8h+XABgjzxqvWafFAe0 kKTrLFJCfrk= =uhXC -----END PGP SIGNATURE-----