CVE-2019-10639

MEDIUM

Description

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

http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00014.html

http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00025.html

https://arxiv.org/pdf/1906.10478.pdf

https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.0.8

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=355b98553789b646ed97ad801a619ff898471b92

https://github.com/torvalds/linux/commit/355b98553789b646ed97ad801a619ff898471b92

https://lists.debian.org/debian-lts-announce/2019/07/msg00022.html

https://lists.debian.org/debian-lts-announce/2019/08/msg00017.html

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://usn.ubuntu.com/4115-1/

https://usn.ubuntu.com/4118-1/

https://www.debian.org/security/2019/dsa-4497

Details

Source: MITRE

Published: 2019-07-05

Updated: 2020-08-24

Type: CWE-326

Risk Information

CVSS v2.0

Base Score: 5

Vector: AV:N/AC:L/Au:N/C:P/I:N/A:N

Impact Score: 2.9

Exploitability Score: 10

Severity: MEDIUM

CVSS v3.0

Base Score: 7.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Impact Score: 3.6

Exploitability Score: 3.9

Severity: HIGH