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Apollo Router Coprocessors may cause Denial-of-Service when handling request bodies

High severity GitHub Reviewed Published Aug 27, 2024 in apollographql/router • Updated Aug 27, 2024

Package

cargo apollo-router (Rust)

Affected versions

>= 1.7.0, < 1.52.1

Patched versions

1.52.1

Description

Impact

Instances of the Apollo Router using either of the following may be impacted by a denial-of-service vulnerability.

  1. External Coprocessing with specific configurations; or
  2. Native Rust Plugins accessing the Router request body in the RouterService layer

Router customizations using Rhai scripts are not impacted.

When using External Coprocessing:

Instances of the Apollo Router running versions >=1.21.0 and <1.52.1 are impacted by a denial-of-service vulnerability if all of the following are true:

  1. Router has been configured to support External Coprocessing.
  2. Router has been configured to send request bodies to coprocessors. This is a non-default configuration and must be configured intentionally by administrators.

You can identify if you are impacted by reviewing your router's configuration YAML for the following config:

...
coprocessor:
  url: http://localhost:9000 # likely different in your environment
  router:
    request:
      body: true # this must be set to 'true' to be impacted
...

External Coprocessing was initially made available as an experimental feature with Router version 1.21.0 on 2023-06-20 and was made generally available with Router version 1.38.0 on 2024-01-19. More information about the Router’s External Coprocessing feature is available here.

When using Native Rust Plugins:

Instances of the Apollo Router running versions >=1.7.0 and <1.52.1 are impacted by a denial-of-service vulnerability if all of the following are true:

  1. Router has been configured to use a custom-developed Native Rust Plugin
  2. The plugin accesses Request.router_request in the RouterService layer
  3. You are accumulating the body from Request.router_request into memory

To use a plugin, you need to be running a customized Router binary. Additionally, you need to have a plugins section with at least one plugin defined in your Router’s configuration YAML. That plugin would also need to define a custom router_service method.

You can check for a defined plugin by reviewing for the following in your Router’s configuration YAML:

...
plugins:
    custom_plugin_name:
        # custom config here
...

You can check for a custom router_service method in a plugin, by reviewing for the following function signature in your plugin’s source:

fn router_service(&self, service: router::BoxService) -> router::BoxService

More information about the Router’s Native Rust Plugin feature is available here.

Impact Detail

If using an impacted configuration, the Router will load entire HTTP request bodies into memory without respect to other HTTP request size-limiting configurations like limits.http_max_request_bytes. This can cause the Router to be out-of-memory (OOM) terminated if a sufficiently large request is sent to the Router.

By default, the Router sets limits.http_max_request_bytes to 2 MB. More information about the Router’s request limiting features is available here.

Patches

Apollo Router 1.52.1

If you have an impacted configuration as defined above, please upgrade to at least Apollo Router 1.52.1.

Workarounds

If you cannot upgrade, you can mitigate the denial-of-service opportunity impacting External Coprocessors by setting the coprocessor.router.request.body configuration option to false. Please note that changing this configuration option will change the information sent to any coprocessors you have configured and may impact functionality implemented by those coprocessors.

If you have developed a Native Rust Plugin and cannot upgrade, you can update your plugin to either not accumulate the request body or enforce a maximum body size limit.

You can also mitigate this issue by limiting HTTP body payload sizes prior to the Router (e.g., in a proxy or web application firewall appliance).

References

Apollo Router 1.52.1 Release Notes
External Coprocessing documentation
HTTP Request Limiting documentation
Native Rust Plugin documentation

References

@jasonbarnett667 jasonbarnett667 published to apollographql/router Aug 27, 2024
Published to the GitHub Advisory Database Aug 27, 2024
Reviewed Aug 27, 2024
Published by the National Vulnerability Database Aug 27, 2024
Last updated Aug 27, 2024

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity None
Availability High
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

EPSS score

0.083%
(36th percentile)

Weaknesses

CVE ID

CVE-2024-43783

GHSA ID

GHSA-x6xq-whh3-gg32

Source code

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