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tgstation-server's DreamMaker environment files outside the deployment directory can be compiled and ran by insufficiently permissioned users

High severity GitHub Reviewed Published Jul 27, 2024 in tgstation/tgstation-server • Updated Aug 8, 2024

Package

nuget Tgstation.Server.Api (NuGet)

Affected versions

>= 4.0.0, < 6.8.0

Patched versions

6.8.0
nuget Tgstation.Server.Host (NuGet)
>= 4.0.0, < 6.8.0
6.8.0

Description

Impact

What kind of vulnerability is it? Who is impacted?

Low permission users using the "Set .dme Path" privilege could potentially set malicious .dme files existing on the host machine to be compiled and executed.

These .dme files could be uploaded via tgstation-server (requiring a separate, isolated privilege) or some other means.

A server configured to execute in BYOND's trusted security level (requiring a third separate, isolated privilege OR being set by another user) could lead to this escalating into remote code execution via BYOND's shell() proc.

The ability to execute this kind of attack is a known side effect of having privileged TGS users, but normally requires multiple privileges with known weaknesses. This vector is not intentional as it does not require control over the where deployment code is sourced from and may not require remote write access to an instance's Configuration directory.

Patches

Has the problem been patched? What versions should users upgrade to?

This problem is patched by pull request #1835 and fixed in versions 6.8.0 and above.

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

Do not give un-trusted users the Deployment permission to set a .dme path on instances.

References

@Cyberboss Cyberboss published to tgstation/tgstation-server Jul 27, 2024
Published by the National Vulnerability Database Jul 29, 2024
Published to the GitHub Advisory Database Jul 29, 2024
Reviewed Jul 29, 2024
Last updated Aug 8, 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 Present
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity Low
Availability High
Subsequent System Impact Metrics
Confidentiality High
Integrity Low
Availability High

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:P/PR:L/UI:N/VC:H/VI:L/VA:H/SC:H/SI:L/SA:H

EPSS score

0.045%
(17th percentile)

Weaknesses

CVE ID

CVE-2024-41799

GHSA ID

GHSA-c3h4-9gc2-f7h4

Source code

Credits

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