#VU22537 Permissions, Privileges, and Access Controls in Xen - CVE-2019-18424
Vulnerability identifier: #VU22537
Vulnerability risk: Low
CVSSv4.0: 2 [CVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]
CVE-ID:
CWE-ID:
CWE-264
Exploitation vector: Local network
Exploit availability: No
Vulnerable software:
Xen
Server applications /
Virtualization software
Vendor: Xen Project
Description
The vulnerability allows a remote user to execute arbitrary code on the target system.
The vulnerability exists due to a boundary error when processing assignment of PCI devices. A privileged user of a guest operating system can program the PCI device to directly access host memory. Once the PCI device is deassigned, the code will be written into host memory. A remote attacker can corrupt host memory and perform denial of service attack or escalate privileges on the system.
Mitigation
Applying the appropriate attached patchset should resolve this issue. For Xen 4.9 and earlier at least the first patch of XSA-299 (whitespace cleanup) is also needed for XSA-302 to apply. Unfortunately, at the time of writing, these patches have not been tested to our satisfaction. The patches are known to break on ARM. ARM is not affected by the issue, so do not apply these patches on ARM systems. (On x86, there is a latent bug but the patches are good to use.) xsa302/*.patch xen-unstable xsa302-4.12/*.patch Xen 4.12.x xsa302-4.11/*.patch Xen 4.11.x xsa302-4.10/*.patch Xen 4.10.x xsa302-4.9/*.patch Xen 4.9.x, Xen 4.8.x $ sha256sum xsa302* xsa302*/* d722d1bed2440a5d35f0fd041e4a77966b7d26980a0f874d38d48710db0b9ebd xsa302.meta 703faced133ca21142f484acd8cf16578258e12ae0cf1413a5d9252f1e099465 xsa302-4.9/0001-IOMMU-add-missing-HVM-check.patch edb4753b91fa66e2f4b51d0075d106fc28d8451241ba482a33c2db4be53f21d1 xsa302-4.9/0002-passthrough-quarantine-PCI-devices.patch 3c79107d8fd94807543443192fb31f3d188912c208f4dbda61f1f2ff92701afc xsa302-4.10/0001-IOMMU-add-missing-HVM-check.patch 2a76add5a907baf0217e57e2a4dca91a6a8ce84c67b9ff87be1bcbb1f29efdc6 xsa302-4.10/0002-passthrough-quarantine-PCI-devices.patch a75723160c52c2c65d563905d0904b587beda1cfb6ca3ee18fb70e79818d3faa xsa302-4.11/0001-IOMMU-add-missing-HVM-check.patch 48b9dae7adbe2438dcaa00f969532d835061cb4a06ab2bf47ada2afb644de4c5 xsa302-4.11/0002-passthrough-quarantine-PCI-devices.patch a21efa6cae14e87318ca3927f0ac310aee2dd1323f2dbf040c0fe80789d78712 xsa302-4.12/0001-IOMMU-add-missing-HVM-check.patch 0a95f750ad1d5eb1838b6488e4ac188acdc2e568eb21b26306d5af2980bffb58 xsa302-4.12/0002-passthrough-quarantine-PCI-devices.patch 11d7015960eab265b1f9ce372dd14597b6c4cc7907d77ed3eed14d161dd50e5c xsa302/0001-passthrough-quarantine-PCI-devices.patch $
Vulnerable software versions
Xen: 4.8.0 - 4.12.1
External links
https://www.openwall.com/lists/oss-security/2019/10/31/6
https://xenbits.xen.org/xsa/advisory-302.html
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated privileged user via the local network (LAN).
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
