Anonymous LDAP Bind

ID

go.anonymous_ldap_bind

Severity

critical

Resource

Access Control

Language

Go

Tags

CWE:862, NIST.SP.800-53, OWASP:2021:A1, PCI-DSS:6.5.8

Description

Anonymous LDAP bind vulnerabilities occur when network applications allow binding to an LDAP server without requiring authentication. This often exposes sensitive directory data to unauthorized users and can lead to security breaches.

Rationale

LDAP (Lightweight Directory Access Protocol) is widely used for accessing and managing directory information services over an IP network. An anonymous LDAP bind refers to allowing connections to the LDAP server without specifying or verifying credentials. This can result in exposing sensitive directory data, as an attacker or unauthorized user can freely query the directory.

Applications that permit anonymous LDAP binds might inadvertently provide attackers access to user information, configuration details, and other sensitive data typically stored in a directory service. This can lead to further exploitation, including the compromise of user accounts or unauthorized access to network resources.

Example of a vulnerable code snippet:

import (
    "log"
    "github.com/go-ldap/ldap/v3"
)

func ldapAnonBind() {
    l, err := ldap.Dial("tcp", "ldap.example.com:389")
    if err != nil {
        log.Fatal(err)
    }
    defer l.Close()

    // Anonymous bind (no DN, no password)
    err = l.Bind("", "")
    if err != nil {
        log.Fatal(err)
    }

    // Proceeding with searches or modifications after anonymous bind
    // could allow unauthorized access
}

This pattern is risky because if the LDAP server permits anonymous bind (which is often enabled for legacy support), the application may bypass authentication mechanisms, exposing it to unauthorized data retrieval or manipulation.

Remediation

To effectively mitigate anonymous LDAP bind vulnerabilities, consider the following remediation strategies:

  • Enforce Strong Authentication: Require all connections to the LDAP server to authenticate using secure credentials. Use Simple Authentication and Security Layer (SASL) or Simple Bind with a username and password.

  • Configure Server Policies: Adjust LDAP server configurations to disallow anonymous binds, ensuring that all incoming connections are authenticated as per the server’s security policies.

  • Access Controls and Auditing: Implement strict access controls within the directory service to ensure that only authorized users can access certain data. Regularly audit access logs to detect any unauthorized or suspicious activities.

  • Connection Encryption: Use Transport Layer Security (TLS) or Secure Sockets Layer (SSL) to encrypt connections to the LDAP server, protecting credentials and data in transit.

By enforcing strict authentication, configuring server policies, and implementing robust access controls, applications can effectively defend against the risks of anonymous LDAP binds, protecting sensitive directory information from unauthorized exposure.

References