Amazon Linux AMI : kernel (ALAS-2021-1503)

high Nessus Plugin ID 149872
New! Plugin Severity Now Using CVSS v3

The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.

Synopsis

The remote Amazon Linux AMI host is missing a security update.

Description

The version of kernel installed on the remote host is prior to 4.14.232-123.381. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS-2021-1503 advisory.

- An issue was discovered in the Linux kernel before 5.7.3, related to mm/gup.c and mm/huge_memory.c. The get_user_pages (aka gup) implementation, when used for a copy-on-write page, does not properly consider the semantics of read operations and therefore can grant unintended write access, aka CID-17839856fd58.
(CVE-2020-29374)

- A race condition in Linux kernel SCTP sockets (net/sctp/socket.c) before 5.12-rc8 can lead to kernel privilege escalation from the context of a network service or an unprivileged process. If sctp_destroy_sock is called without sock_net(sk)->sctp.addr_wq_lock then an element is removed from the auto_asconf_splist list without any proper locking. This can be exploited by an attacker with network service privileges to escalate to root or from the context of an unprivileged user directly if a BPF_CGROUP_INET_SOCK_CREATE is attached which denies creation of some SCTP socket. (CVE-2021-23133)

- The fix for XSA-365 includes initialization of pointers such that subsequent cleanup code wouldn't use uninitialized or stale values. This initialization went too far and may under certain conditions also overwrite pointers which are in need of cleaning up. The lack of cleanup would result in leaking persistent grants. The leak in turn would prevent fully cleaning up after a respective guest has died, leaving around zombie domains. All Linux versions having the fix for XSA-365 applied are vulnerable.
XSA-365 was classified to affect versions back to at least 3.11. (CVE-2021-28688)

- A race condition was discovered in get_old_root in fs/btrfs/ctree.c in the Linux kernel through 5.11.8. It allows attackers to cause a denial of service (BUG) because of a lack of locking on an extent buffer before a cloning operation, aka CID-dbcc7d57bffc. (CVE-2021-28964)

- In intel_pmu_drain_pebs_nhm in arch/x86/events/intel/ds.c in the Linux kernel through 5.11.8 on some Haswell CPUs, userspace applications (such as perf-fuzzer) can cause a system crash because the PEBS status in a PEBS record is mishandled, aka CID-d88d05a9e0b6. (CVE-2021-28971)

- BPF JIT compilers in the Linux kernel through 5.11.12 have incorrect computation of branch displacements, allowing them to execute arbitrary code within the kernel context. This affects arch/x86/net/bpf_jit_comp.c and arch/x86/net/bpf_jit_comp32.c. (CVE-2021-29154)

- An issue was discovered in the Linux kernel through 5.11.x. kernel/bpf/verifier.c performs undesirable out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations and obtain sensitive information from kernel memory. Specifically, for sequences of pointer arithmetic operations, the pointer modification performed by the first operation is not correctly accounted for when restricting subsequent operations. (CVE-2021-29155)

- kernel/bpf/verifier.c in the Linux kernel through 5.12.1 performs undesirable speculative loads, leading to disclosure of stack content via side-channel attacks, aka CID-801c6058d14a. The specific concern is not protecting the BPF stack area against speculative loads. Also, the BPF stack can contain uninitialized data that might represent sensitive information previously operated on by the kernel. (CVE-2021-31829)

- An out-of-bounds (OOB) memory write flaw was found in list_devices in drivers/md/dm-ioctl.c in the Multi- device driver module in the Linux kernel before 5.12. A bound check failure allows an attacker with special user (CAP_SYS_ADMIN) privilege to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability. (CVE-2021-31916)

- The Linux kernel before 5.11.14 has a use-after-free in cipso_v4_genopt in net/ipv4/cipso_ipv4.c because the CIPSO and CALIPSO refcounting for the DOI definitions is mishandled, aka CID-ad5d07f4a9cd. This leads to writing an arbitrary value. (CVE-2021-33033)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update kernel' to update your system.

See Also

https://alas.aws.amazon.com/ALAS-2021-1503.html

https://access.redhat.com/security/cve/CVE-2020-25670

https://access.redhat.com/security/cve/CVE-2020-25671

https://access.redhat.com/security/cve/CVE-2020-25672

https://access.redhat.com/security/cve/CVE-2020-25673

https://access.redhat.com/security/cve/CVE-2020-29374

https://access.redhat.com/security/cve/CVE-2021-23133

https://access.redhat.com/security/cve/CVE-2021-28688

https://access.redhat.com/security/cve/CVE-2021-28964

https://access.redhat.com/security/cve/CVE-2021-28971

https://access.redhat.com/security/cve/CVE-2021-29154

https://access.redhat.com/security/cve/CVE-2021-29155

https://access.redhat.com/security/cve/CVE-2021-31829

https://access.redhat.com/security/cve/CVE-2021-31916

https://access.redhat.com/security/cve/CVE-2021-33033

Plugin Details

Severity: High

ID: 149872

File Name: ala_ALAS-2021-1503.nasl

Version: 1.2

Type: local

Agent: unix

Published: 5/24/2021

Updated: 5/24/2021

Dependencies: ssh_get_info.nasl

Risk Information

CVSS Score Source: CVE-2021-29154

VPR

Risk Factor: Critical

Score: 9

CVSS v2

Risk Factor: High

Base Score: 7.2

Temporal Score: 5.3

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

Temporal Vector: E:U/RL:OF/RC:C

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

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

Temporal Vector: E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:kernel, p-cpe:/a:amazon:linux:kernel-debuginfo, p-cpe:/a:amazon:linux:kernel-debuginfo-common-i686, p-cpe:/a:amazon:linux:kernel-debuginfo-common-x86_64, p-cpe:/a:amazon:linux:kernel-devel, p-cpe:/a:amazon:linux:kernel-headers, p-cpe:/a:amazon:linux:kernel-tools, p-cpe:/a:amazon:linux:kernel-tools-debuginfo, p-cpe:/a:amazon:linux:kernel-tools-devel, p-cpe:/a:amazon:linux:perf, p-cpe:/a:amazon:linux:perf-debuginfo, cpe:/o:amazon:linux

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 5/20/2021

Vulnerability Publication Date: 11/28/2020

Reference Information

CVE: CVE-2020-25670, CVE-2020-25671, CVE-2020-25672, CVE-2020-25673, CVE-2020-29374, CVE-2021-23133, CVE-2021-28688, CVE-2021-28964, CVE-2021-28971, CVE-2021-29154, CVE-2021-29155, CVE-2021-31829, CVE-2021-31916, CVE-2021-33033

ALAS: 2021-1503