CVE Vulnerabilities

CVE-2020-6959

Deserialization of Untrusted Data

Published: Jan 22, 2020 | Modified: Feb 05, 2020
CVSS 3.x
9.8
CRITICAL
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
7.5 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P
RedHat/V2
RedHat/V3
Ubuntu

The following versions of MAXPRO VMS and NVR, MAXPRO VMS:HNMSWVMS prior to Version VMS560 Build 595 T2-Patch, HNMSWVMSLT prior to Version VMS560 Build 595 T2-Patch, MAXPRO NVR: MAXPRO NVR XE prior to Version NVR 5.6 Build 595 T2-Patch, MAXPRO NVR SE prior to Version NVR 5.6 Build 595 T2-Patch, MAXPRO NVR PE prior to Version NVR 5.6 Build 595 T2-Patch, and MPNVRSWXX prior to Version NVR 5.6 Build 595 T2-Patch are vulnerable to an unsafe deserialization of untrusted data. An attacker may be able to remotely modify deserialized data without authentication using a specially crafted web request, resulting in remote code execution.

Weakness

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

Affected Software

Name Vendor Start Version End Version
Maxpro_nvr_xe_firmware Honeywell * 5.6 (including)

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