Important: kernel

Issue Overview:

A security flaw was found in the chap_server_compute_md5() function in the ISCSI target code in the Linux kernel in a way an authentication request from an ISCSI initiator is processed. An unauthenticated remote attacker can cause a stack buffer overflow and smash up to 17 bytes of the stack. The attack requires the iSCSI target to be enabled on the victim host. Depending on how the target’s code was built (i.e. depending on a compiler, compile flags and hardware architecture) an attack may lead to a system crash and thus to a denial-of-service or possibly to a non-authorized access to data exported by an iSCSI target. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although we believe it is highly unlikely.(CVE-2018-14633)

An information leak was discovered in the Linux kernel in cdrom_ioctl_drive_status() function in drivers/cdrom/cdrom.c that could be used by local attackers to read kernel memory at certain location.(CVE-2018-16658)

A security flaw was discovered in the Linux kernel. The vmacache_flush_all() function in mm/vmacache.c mishandles sequence number overflows. An attacker can trigger a use-after-free (and possibly gain privileges) via certain thread creation, map, unmap, invalidation, and dereference operations.(CVE-2018-17182)

A flaw was found in the Linux kernels block driver implementation (blk_drain_queue() function) where a use-after-free condition could be triggered while draining the outstanding command queue in the systems block device subsystem. An attacker could use this flaw to crash the system or corrupt local memory, which may lead to privilege escalation.(CVE-2018-20856)

Affected Packages:

kernel

Issue Correction:
Run yum update kernel and reboot your instance to update your system.

New Packages:

i686:  
    kernel-debuginfo-common-i686-4.14.72-68.55.amzn1.i686  
    kernel-headers-4.14.72-68.55.amzn1.i686  
    kernel-tools-devel-4.14.72-68.55.amzn1.i686  
    kernel-4.14.72-68.55.amzn1.i686  
    kernel-tools-4.14.72-68.55.amzn1.i686  
    perf-4.14.72-68.55.amzn1.i686  
    kernel-debuginfo-4.14.72-68.55.amzn1.i686  
    kernel-tools-debuginfo-4.14.72-68.55.amzn1.i686  
    kernel-devel-4.14.72-68.55.amzn1.i686  
    perf-debuginfo-4.14.72-68.55.amzn1.i686  
  
src:  
    kernel-4.14.72-68.55.amzn1.src  
  
x86_64:  
    kernel-debuginfo-4.14.72-68.55.amzn1.x86_64  
    perf-debuginfo-4.14.72-68.55.amzn1.x86_64  
    perf-4.14.72-68.55.amzn1.x86_64  
    kernel-devel-4.14.72-68.55.amzn1.x86_64  
    kernel-tools-debuginfo-4.14.72-68.55.amzn1.x86_64  
    kernel-tools-4.14.72-68.55.amzn1.x86_64  
    kernel-headers-4.14.72-68.55.amzn1.x86_64  
    kernel-4.14.72-68.55.amzn1.x86_64  
    kernel-tools-devel-4.14.72-68.55.amzn1.x86_64  
    kernel-debuginfo-common-x86_64-4.14.72-68.55.amzn1.x86_64  

Additional References

Red Hat: CVE-2018-14633, CVE-2018-16658, CVE-2018-17182, CVE-2018-20856

Mitre: CVE-2018-14633, CVE-2018-16658, CVE-2018-17182, CVE-2018-20856