CVE-2024-5590: Netentsec Security Gateway SQLi Flaw

CVE-2024-5590 Overview

CVE-2024-5590 is a SQL injection vulnerability in Netentsec NS-ASG Application Security Gateway 6.3. The flaw resides in the JSON Content Handler component, specifically in /protocol/iscuser/uploadiscuser.php. Attackers can manipulate the messagecontent parameter to inject arbitrary SQL statements against the backing database. The vulnerability is exploitable remotely over the network and requires low privileges. Public disclosure occurred through VulDB entry VDB-266848, and a proof-of-concept is available in a public GitHub repository. The vendor was contacted prior to disclosure but did not respond. The weakness is classified under [CWE-89] (Improper Neutralization of Special Elements used in an SQL Command).

Critical Impact

Authenticated remote attackers can inject SQL through the messagecontent argument, enabling unauthorized read or modification of data stored by the NS-ASG appliance.

Affected Products

• Netentsec NS-ASG Application Security Gateway 6.3
• Component: JSON Content Handler (/protocol/iscuser/uploadiscuser.php)
• Vulnerable parameter: messagecontent

Discovery Timeline

• 2024-06-03 - CVE-2024-5590 published to NVD
• 2025-02-07 - Last updated in NVD database

Technical Details for CVE-2024-5590

Vulnerability Analysis

The vulnerability is a SQL injection flaw in the JSON Content Handler of NS-ASG 6.3. The uploadiscuser.php endpoint processes JSON-formatted requests and passes the messagecontent value into a SQL statement without proper sanitization or parameterization. An attacker who can reach the appliance over the network and supply low-privilege credentials can manipulate the parameter to alter query semantics. Successful exploitation allows reading sensitive data, modifying records, or otherwise interacting with the underlying database. According to EPSS data, the probability of exploitation in the wild is 0.053%.

Root Cause

The root cause is the absence of input validation and prepared statements in uploadiscuser.php. The handler concatenates the messagecontent value from the inbound JSON payload directly into a SQL query string. This pattern allows characters such as single quotes, comments, and UNION operators to escape the intended query context. The defect aligns with [CWE-89].

Attack Vector

The attack is initiated remotely against the management interface of the NS-ASG appliance. An attacker submits a crafted HTTP POST request to /protocol/iscuser/uploadiscuser.php containing a JSON body where the messagecontent field carries SQL syntax. The injected payload is executed by the database server, returning attacker-controlled query results or performing unintended writes. No verified exploit code is reproduced here; refer to the GitHub PoC Repository for technical write-up details and to VulDB #266848 for additional context.

Detection Methods for CVE-2024-5590

Indicators of Compromise

• HTTP POST requests to /protocol/iscuser/uploadiscuser.php containing SQL metacharacters such as ', --, UNION, or SLEEP( inside the messagecontent JSON field.
• Unexpected database errors logged by the NS-ASG appliance that reference the uploadiscuser code path.
• Anomalous outbound queries or large response payloads originating from the gateway database immediately after requests to the JSON Content Handler.

Detection Strategies

• Deploy web application firewall signatures that inspect JSON bodies posted to /protocol/iscuser/uploadiscuser.php and flag SQL syntax in the messagecontent field.
• Correlate authentication events with subsequent requests to the vulnerable endpoint to identify low-privilege accounts probing the parameter.
• Hunt for repeated requests to the endpoint that produce HTTP 500 errors or unusually large responses, both common SQL injection symptoms.

Monitoring Recommendations

• Forward NS-ASG access and error logs to a centralized log platform and alert on requests to uploadiscuser.php that contain SQL keywords.
• Monitor database audit logs for query patterns referencing iscuser tables outside of normal administrative workflows.
• Track authentication failures and account lockouts on the management interface to identify credential stuffing that may precede exploitation.

How to Mitigate CVE-2024-5590

Immediate Actions Required

• Restrict network access to the NS-ASG management interface so only trusted administrative networks can reach /protocol/iscuser/uploadiscuser.php.
• Rotate credentials for any account permitted to authenticate to the appliance, since low-privilege accounts are sufficient to exploit the flaw.
• Review database and appliance logs for prior requests to the vulnerable endpoint containing SQL syntax in the messagecontent field.

Patch Information

No vendor patch has been published. According to the NVD entry and VulDB, Netentsec was contacted before public disclosure but did not respond. Until an official fix is released, operators should rely on compensating controls. Monitor the VulDB CTI ID #266848 entry and the vendor portal for future advisories.

Workarounds

• Place the NS-ASG management interface behind a VPN or jump host and block direct internet exposure.
• Deploy a reverse proxy or WAF rule that rejects requests to /protocol/iscuser/uploadiscuser.php containing SQL metacharacters in messagecontent.
• Limit the database account used by NS-ASG to the minimum privileges required, reducing the blast radius of a successful injection.
• If the JSON Content Handler is not required, disable or remove the endpoint at the web server layer.

# Example nginx rule to block SQL metacharacters posted to the vulnerable endpoint
location = /protocol/iscuser/uploadiscuser.php {
    if ($request_body ~* "(\bunion\b|\bselect\b|--|;|sleep\(|benchmark\()") {
        return 403;
    }
    proxy_pass http://ns_asg_backend;
}