CVE Vulnerabilities

CVE-2020-35534

Allocation of Resources Without Limits or Throttling

Published: Sep 01, 2022 | Modified: Sep 07, 2022
CVSS 3.x
5.5
MEDIUM
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS 2.x
RedHat/V2
RedHat/V3
5.5 LOW
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Ubuntu
MEDIUM

In LibRaw, there is a memory corruption vulnerability within the crxFreeSubbandData() function (librawsrcdecoderscrx.cpp) when processing cr3 files.

Weakness

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.

Affected Software

Name Vendor Start Version End Version
Libraw Libraw 0.20.0 (including) 0.20.0 (including)
Libraw Libraw 0.20.0-rc2 (including) 0.20.0-rc2 (including)
Libraw Libraw 0.20.1 (including) 0.20.1 (including)
Libraw Libraw 0.20.2 (including) 0.20.2 (including)
Libraw Libraw 0.21.0-beta1 (including) 0.21.0-beta1 (including)
Darktable Ubuntu bionic *
Darktable Ubuntu kinetic *
Darktable Ubuntu lunar *
Darktable Ubuntu mantic *
Darktable Ubuntu trusty *
Darktable Ubuntu xenial *
Dcraw Ubuntu bionic *
Dcraw Ubuntu kinetic *
Dcraw Ubuntu lunar *
Dcraw Ubuntu mantic *
Dcraw Ubuntu trusty *
Dcraw Ubuntu xenial *
Digikam Ubuntu bionic *
Digikam Ubuntu kinetic *
Digikam Ubuntu lunar *
Digikam Ubuntu mantic *
Digikam Ubuntu trusty *
Digikam Ubuntu xenial *
Exactimage Ubuntu bionic *
Exactimage Ubuntu kinetic *
Exactimage Ubuntu lunar *
Exactimage Ubuntu mantic *
Exactimage Ubuntu trusty *
Exactimage Ubuntu xenial *
Kodi Ubuntu bionic *
Kodi Ubuntu kinetic *
Kodi Ubuntu lunar *
Kodi Ubuntu mantic *
Kodi Ubuntu xenial *
Libraw Ubuntu trusty *
Libraw Ubuntu upstream *
Libraw Ubuntu xenial *
Rawtherapee Ubuntu bionic *
Rawtherapee Ubuntu kinetic *
Rawtherapee Ubuntu lunar *
Rawtherapee Ubuntu mantic *
Rawtherapee Ubuntu trusty *
Rawtherapee Ubuntu xenial *
Ufraw Ubuntu bionic *
Ufraw Ubuntu trusty *
Ufraw Ubuntu xenial *
Xbmc Ubuntu trusty *

Extended Description

Code frequently has to work with limited resources, so programmers must be careful to ensure that resources are not consumed too quickly, or too easily. Without use of quotas, resource limits, or other protection mechanisms, it can be easy for an attacker to consume many resources by rapidly making many requests, or causing larger resources to be used than is needed. When too many resources are allocated, or if a single resource is too large, then it can prevent the code from working correctly, possibly leading to a denial of service.

Potential Mitigations

  • Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”

  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

  • Mitigation of resource exhaustion attacks requires that the target system either:

  • The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

  • The second solution can be difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply requires more resources on the part of the attacker.

  • If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery.

  • Ensure that all failures in resource allocation place the system into a safe posture.

  • Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems.

  • When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users.

  • Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).

References