Ldap Injection in Gin with Cockroachdb

Ldap Injection occurs when untrusted input is concatenated into LDAP filter strings, allowing attackers to manipulate the query logic. When using the Gin web framework with Cockroachdb as a backend datastore, this risk arises if user-supplied values (e.g., username or email) are used to construct LDAP queries without proper escaping. Cockroachdb, while PostgreSQL-wire compatible, does not inherently sanitize inputs for LDAP contexts; it simply passes values to the LDAP server if used as an identity store. This combination becomes vulnerable when developers build dynamic filter strings like (&(uid=USER_INPUT)) directly in Go code using string formatting. An attacker can supply *) (&(objectClass=*) as input, potentially bypassing authentication or extracting other directory entries depending on server configuration.

In a Gin application, routes might accept query parameters that are forwarded to an LDAP client library. For example, a login handler could read username and password from form data and build an LDAP search filter by concatenating strings. Because Cockroachdb is not involved in LDAP protocol operations, the vulnerability is not in Cockroachdb itself but in how the application builds LDAP filter strings before contacting an LDAP server. However, if the application stores or references directory configuration (such as base DN or filter templates) in Cockroachdb, compromised data or misconfigured stored queries could exacerbate injection risks by providing malicious templates or enabling secondary injection paths.

Real-world impact includes unauthorized authentication bypass, information disclosure, or possible account compromise. This aligns with OWASP API Top 10 controls around authentication and input validation. Because middleBrick scans test unauthenticated attack surfaces, it can detect LDAP injection patterns in endpoints that accept user input for directory queries, even when Cockroachdb is used only for metadata or configuration storage.

Remediation centers on strict input validation and parameterized approaches. Avoid building LDAP filter strings via concatenation. Instead, use dedicated LDAP escaping functions for each user-supplied value. In Go, the gopkg.in/ldap.v3 library provides utilities to help construct safe filters, but developers must still apply escaping for substrings used in attributes like uid or mail.

Below are concrete code examples for a Gin handler that safely handles user input against an LDAP service while using Cockroachdb only for non-sensitive configuration storage.

package main

import (
    "github.com/gin-gonic/gin"
    "github.com/gopkg.in/ldap.v3"
    "net/http"
)

// SafeLDAPSearch builds a filter with proper escaping.
func SafeLDAPSearch(username string) (string, error) {
    // ldap.EscapeFilter escapes special characters for RFC4515 LDAP filters.
    escaped, err := ldap.EscapeFilter(username)
    if err != nil {
        return "", err
    }
    // Use parameterized-style construction by embedding escaped value.
    filter := "(&(uid=" + escaped + "))"
    return filter, nil
}

func loginHandler(c *gin.Context) {
    username := c.PostForm("username")
    password := c.PostForm("password")

    filter, err := SafeLDAPSearch(username)
    if err != nil {
        c.JSON(http.StatusBadRequest, gin.H{"error": "invalid input"})
        return
    }

    // Example LDAP connection and bind (pseudocode, adapt to your LDAP client).
    // l, err := ldap.Dial("tcp", "ldap.example.com:389")
    // if err != nil { /* handle */ }
    // defer l.Close()
    // err = l.Bind("cn="+filter+",dc=example,dc=com", password)
    if err != nil {
        c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
        return
    }

    c.JSON(http.StatusOK, gin.H{"status": "ok"})
}

If configuration such as base DN is stored in Cockroachdb, ensure it is validated and not directly concatenated into LDAP filters. Use parameterized queries when reading from Cockroachdb to avoid SQL injection, which is a separate concern but often co-located in the same codebase.

Finally, apply least-privilege principles to the LDAP service account and implement rate limiting in Gin to reduce brute-force risks. middleBrick can help identify LDAP injection patterns and related misconfigurations during scans, providing remediation guidance aligned with frameworks like OWASP API Top 10.