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LTI 1.3 Grade Pass Back Implementation has Missing Authorization Vulnerability

Low severity GitHub Reviewed Published Jan 24, 2023 in openedx/xblock-lti-consumer • Updated Aug 30, 2024

Package

pip lti-consumer-xblock (pip)

Affected versions

>= 7.0.0, < 7.2.2

Patched versions

7.2.2

Description

Problem

TL;DR: Any LTI tool that is integrated with on the Open edX platform can
post a grade back for any LTI XBlock so long as it knows or can guess the
block location for that XBlock.

In LTI 1.3, LTI tools can "pass back" scores that learners earn while using
LTI tools to the edX platform. The edX platform then stores those LTI
scores in a separate table. If the right conditions are met, these scores
are then persisted to the LMS grades tables.

LTI tools can create what are called "line items" on the edX platform. A
line item can be thought of as a column in a grade book; it stores results
for a specific activity (i.e. XBlock) for a specific set of users (i.e.
users in the course using the XBlock). A line item has an optional
resource_link_id field, which is basically the XBlock location. An LTI tool
can supply any value for this field.

An LTI tool submits scores to the edX platform for line items. The code
that uploads that score to the LMS grade tables determines which XBlock to
upload the grades for by reading the resource_link_id field of the
associated line item. Because the LTI tool could have submitted any value
for the resource_link_id field, this introduces the potential for a
nefarious LTI tool to submit scores for any LTI XBlock on the platform.

Impact

Any LTI tool that is integrated with on the Open edX platform can post a
grade back for any LTI XBlock so long as it knows the resource_link_id
(i.e. block location) for that XBlock.

The impact is a loss of integrity for LTI XBlock grades.

Patches

No available patch

Workarounds

No

References

@alangsto alangsto published to openedx/xblock-lti-consumer Jan 24, 2023
Published by the National Vulnerability Database Jan 26, 2023
Published to the GitHub Advisory Database Aug 30, 2024
Reviewed Aug 30, 2024
Last updated Aug 30, 2024

Severity

Low

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 Passive
Vulnerable System Impact Metrics
Confidentiality Low
Integrity Low
Availability None
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:P/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

EPSS score

0.050%
(21st percentile)

Weaknesses

CVE ID

CVE-2023-23611

GHSA ID

GHSA-7j9p-67mm-5g87

Source code

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