CVE-2024-43397

Executive Summary

CVE-2024-43397 is a medium-severity authorization bypass vulnerability in Apollo, a popular configuration management system. The flaw resides in the synchronization configuration feature, allowing authenticated users to craft specific HTTP requests that bypass permission checks and modify namespaces they should not have access to. The vulnerability was addressed in Apollo version 2.3.0 by adding an input parameter validation check. With a CVSS score of 4.3 and an EPSS score of 0.0%, exploitation is currently not widespread, but the risk of unauthorized configuration tampering remains significant for unpatched instances.

Supply Chain & Package Security

Apollo is a Java-based configuration management system commonly deployed in enterprise environments. Organizations using Apollo should verify their deployment version and apply the patch immediately. The vulnerability does not affect the package distribution itself but rather the runtime authorization logic.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (authenticated user)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: Low (unauthorized modification of namespace)
• Availability Impact: None

Threat Level: Medium. While the CVSS score is moderate, the ability to modify configuration namespaces could lead to cascading security issues if attackers inject malicious configurations.

Deep Dive & Mechanics

The vulnerability exists in the synchronization configuration endpoint of Apollo's portal. The feature allows administrators to synchronize namespace configurations across environments. Due to missing authorization checks on the input parameters, an authenticated user with limited privileges can craft a request that modifies a namespace they do not own.

Root Cause: The synchronization endpoint did not validate whether the requesting user had the necessary permissions on the target namespace. By manipulating parameters such as namespaceId or appId, an attacker could bypass the intended access controls.

Attack Flow:

1. Attacker authenticates as a low-privileged user.
2. Attacker identifies a target namespace (e.g., via enumeration or known IDs).
3. Attacker sends a crafted POST request to the synchronization endpoint with the target namespace ID.
4. The server processes the request without verifying permissions, modifying the namespace configuration.

Vulnerable vs. Patched Code

Vulnerable Code (Pre-2.3.0):

// No permission check on target namespace
@RequestMapping(value = "/sync", method = RequestMethod.POST)
public void syncNamespace(@RequestParam String appId, @RequestParam String namespaceId) {
    // Directly syncs without verifying user permissions
    namespaceService.sync(appId, namespaceId);
}

Patched Code (2.3.0):

@RequestMapping(value = "/sync", method = RequestMethod.POST)
public void syncNamespace(@RequestParam String appId, @RequestParam String namespaceId, HttpServletRequest request) {
    // Verify user has permission on the target namespace
    User user = getUserFromRequest(request);
    if (!permissionService.hasNamespacePermission(user, appId, namespaceId)) {
        throw new AccessDeniedException("Insufficient permissions");
    }
    namespaceService.sync(appId, namespaceId);
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to an Apollo portal instance (version < 2.3.0)
• Valid low-privileged user credentials
• Knowledge of a target namespace ID (e.g., via enumeration)

Exploitation Steps:

1. Authenticate and obtain a session cookie.
2. Identify target namespace ID (e.g., namespaceId=100).
3. Send a crafted POST request:

curl -X POST "http://target-apollo-portal/namespaces/sync" \
  -H "Cookie: SESSION=valid_session_cookie" \
  -d "appId=target-app&namespaceId=100"

4. Verify the namespace configuration has been modified.

Note: No public exploit code is available at this time.

Blue Team

Detection:

• Monitor for unusual POST requests to /namespaces/sync endpoint.
• Alert on synchronization attempts by users without namespace admin roles.
• Review logs for AccessDeniedException errors (indicating blocked attempts after patch).

Hunting:

• Search for namespaceId parameters in logs that do not match the user's authorized namespaces.
• Correlate synchronization events with user privilege levels.

Indicators of Compromise (IOCs)

• Network: POST requests to /namespaces/sync with unexpected namespaceId values.
• Logs: AccessDeniedException or Insufficient permissions errors from the synchronization endpoint.
• System: Unauthorized changes to namespace configurations in Apollo.

Detection Engineering

YARA Rule

rule CVE_2024_43397_Apollo_Sync_Bypass {
    meta:
        description = "Detects exploitation attempts of CVE-2024-43397 in Apollo logs"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-43397"
    strings:
        $sync_endpoint = "/namespaces/sync"
        $namespace_param = "namespaceId="
        $app_param = "appId="
    condition:
        $sync_endpoint and $namespace_param and $app_param
}

Sigma Rule

title: Apollo Namespace Sync Authorization Bypass
id: cve-2024-43397
status: experimental
description: Detects unauthorized namespace synchronization attempts
logsource:
    category: web
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/namespaces/sync'
        cs-uri-query|contains: 'namespaceId='
    condition: selection
falsepositives:
    - Legitimate admin synchronization
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-43397 Apollo Namespace Sync Bypass"; flow:to_server,established; http.method; content:"POST"; http.uri; content:"/namespaces/sync"; http.client_body; content:"namespaceId="; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade Apollo to version 2.3.0 or later.
2. If upgrade is not possible, restrict access to the synchronization endpoint via network ACLs or WAF rules.
3. Review and audit all namespace configurations for unauthorized changes.

Long-term Measures:

• Implement role-based access control (RBAC) reviews.
• Enable detailed audit logging for all configuration changes.
• Regularly scan for known vulnerabilities using tools like Nessus or OpenVAS.

Workaround:

• Disable the synchronization feature if not in use by setting apollo.sync.enabled=false in the configuration.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert