Information Exposure Affecting kernel-headers package, versions <0:4.18.0-193.el8
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-RHEL8-KERNELHEADERS-3742486
- published26 Jul 2021
- disclosed15 Jul 2019
Introduced: 15 Jul 2019
CVE-2019-10639 (opens in a new tab)How to fix?
Upgrade RHEL:8 kernel-headers to version 0:4.18.0-193.el8 or higher.
This issue was patched in RHSA-2020:1769.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-headers package and not the kernel-headers package as distributed by RHEL.
See How to fix? for RHEL:8 relevant fixed versions and status.
The Linux kernel 4.x (starting from 4.1) and 5.x before 5.0.8 allows Information Exposure (partial kernel address disclosure), leading to a KASLR bypass. Specifically, it is possible to extract the KASLR kernel image offset using the IP ID values the kernel produces for connection-less protocols (e.g., UDP and ICMP). When such traffic is sent to multiple destination IP addresses, it is possible to obtain hash collisions (of indices to the counter array) and thereby obtain the hashing key (via enumeration). This key contains enough bits from a kernel address (of a static variable) so when the key is extracted (via enumeration), the offset of the kernel image is exposed. This attack can be carried out remotely, by the attacker forcing the target device to send UDP or ICMP (or certain other) traffic to attacker-controlled IP addresses. Forcing a server to send UDP traffic is trivial if the server is a DNS server. ICMP traffic is trivial if the server answers ICMP Echo requests (ping). For client targets, if the target visits the attacker's web page, then WebRTC or gQUIC can be used to force UDP traffic to attacker-controlled IP addresses. NOTE: this attack against KASLR became viable in 4.1 because IP ID generation was changed to have a dependency on an address associated with a network namespace.
References
- https://seclists.org/bugtraq/2019/Aug/18
- https://security.netapp.com/advisory/ntap-20190806-0001/
- https://support.f5.com/csp/article/K32804955
- https://support.f5.com/csp/article/K32804955?utm_source=f5support&utm_medium=RSS
- https://access.redhat.com/security/cve/CVE-2019-10639
- https://www.debian.org/security/2019/dsa-4497
- https://arxiv.org/pdf/1906.10478.pdf
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.0.8
- https://github.com/torvalds/linux/commit/355b98553789b646ed97ad801a619ff898471b92
- https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=355b98553789b646ed97ad801a619ff898471b92
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://lists.debian.org/debian-lts-announce/2019/07/msg00022.html
- https://lists.debian.org/debian-lts-announce/2019/08/msg00017.html
- https://access.redhat.com/errata/RHSA-2020:1769
- http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00014.html
- http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00025.html
- https://usn.ubuntu.com/4115-1/
- https://usn.ubuntu.com/4118-1/
- https://support.f5.com/csp/article/K32804955?utm_source=f5support&%3Butm_medium=RSS