CVE Vulnerabilities

CVE-2018-15686

Deserialization of Untrusted Data

Published: Oct 26, 2018 | Modified: Nov 07, 2023
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
7.2 HIGH
AV:L/AC:L/Au:N/C:C/I:C/A:C
RedHat/V2
RedHat/V3
3.6 MODERATE
CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L
Ubuntu
MEDIUM

A vulnerability in unit_deserialize of systemd allows an attacker to supply arbitrary state across systemd re-execution via NotifyAccess. This can be used to improperly influence systemd execution and possibly lead to root privilege escalation. Affected releases are systemd versions up to and including 239.

Weakness

The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.

Affected Software

Name Vendor Start Version End Version
Ubuntu_linux Canonical 16.04 (including) 16.04 (including)
Ubuntu_linux Canonical 18.04 (including) 18.04 (including)
Ubuntu_linux Canonical 18.10 (including) 18.10 (including)
Debian_linux Debian 8.0 (including) 8.0 (including)
Red Hat Ansible Tower 3.4 for RHEL 7 RedHat ansible-tower-34/ansible-tower-memcached:1.4.15-28 *
Red Hat Ansible Tower 3.4 for RHEL 7 RedHat ansible-tower-35/ansible-tower-memcached:1.4.15-28 *
Red Hat Ansible Tower 3.4 for RHEL 7 RedHat ansible-tower-37/ansible-tower-memcached-rhel7:1.4.15-28 *
Red Hat Enterprise Linux 7 RedHat systemd-0:219-67.el7 *
Red Hat Enterprise Linux 7.4 Advanced Update Support RedHat systemd-0:219-42.el7_4.20 *
Red Hat Enterprise Linux 7.4 Telco Extended Update Support RedHat systemd-0:219-42.el7_4.20 *
Red Hat Enterprise Linux 7.4 Update Services for SAP Solutions RedHat systemd-0:219-42.el7_4.20 *
Red Hat Enterprise Linux 7.5 Extended Update Support RedHat systemd-0:219-57.el7_5.9 *
Red Hat Enterprise Linux 7.6 Extended Update Support RedHat systemd-0:219-62.el7_6.11 *
Systemd Ubuntu bionic *
Systemd Ubuntu cosmic *
Systemd Ubuntu devel *
Systemd Ubuntu upstream *
Systemd Ubuntu xenial *

Extended Description

It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.

Potential Mitigations

  • Make fields transient to protect them from deserialization.
  • An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.

References