Ldap Injection in Echo Go

LDAP injection in Echo Go applications typically occurs when user input is concatenated directly into LDAP search filters without proper sanitization. In Echo Go's common authentication and authorization patterns, this vulnerability often appears in directory service integrations where user credentials or search parameters are processed.

A typical vulnerable pattern in Echo Go looks like this:

func authenticate(c echo.Context) error {
    username := c.FormValue("username")
    password := c.FormValue("password")
    
    filter := fmt.Sprintf("(uid=%s)", username)
    
    searchRequest := ldap.NewSearchRequest(
        "dc=example,dc=com",
        ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false,
        filter,
        []string{"uid", "cn", "sn"},
        nil,
    )
    
    sr, err := connection.Search(searchRequest)
    if err != nil {
        return echo.NewHTTPError(http.StatusInternalServerError, "Authentication failed")
    }
    
    // Process results...
    return c.JSON(http.StatusOK, map[string]string{"status": "authenticated"})
}

The vulnerability here is the direct interpolation of the username variable into the LDAP filter string. An attacker can craft a username like:

username = "*")) (&(objectClass=*)(uid=*))

This breaks out of the intended filter context and creates a new filter that returns all users, potentially bypassing authentication entirely. The double parentheses and additional operators manipulate the LDAP query structure.

Echo Go's middleware-based architecture can compound this issue when authentication middleware constructs LDAP queries dynamically. Consider this middleware pattern:

func LDAPAuthMiddleware(next echo.HandlerFunc) echo.HandlerFunc {
    return func(c echo.Context) error {
        token := c.Request().Header.Get("Authorization")
        
        // Vulnerable: direct concatenation of token
        filter := "(token=" + token + ")"
        
        searchRequest := ldap.NewSearchRequest(
            "ou=users,dc=example,dc=com",
            ldap.ScopeSingleLevel, ldap.NeverDerefAliases, 0, 0, false,
            filter,
            []string{"dn", "token"},
            nil,
        )
        
        // Search and validate...
        return next(c)
    }
}

An attacker can inject LDAP operators through the Authorization header, potentially enumerating users or accessing unauthorized resources. The middleware pattern is particularly dangerous because it processes every request before routing, giving attackers a consistent injection point.

Echo Go's parameter binding also creates injection opportunities. When using c.Bind() or c.FormValue() with struct tags, developers might construct LDAP queries from bound data:

type SearchParams struct {
    Username string `form:"username"`
    Department string `form:"department"`
}

func searchUsers(c echo.Context) error {
    var params SearchParams
    if err := c.Bind(&params); err != nil {
        return err
    }
    
    filter := fmt.Sprintf("(&(uid=%s)(department=%s))", 
        params.Username, params.Department)
    
    // LDAP search with constructed filter...
    return c.JSON(http.StatusOK, results)
}

This pattern allows injection through either parameter, as both are directly concatenated into the filter string without validation or escaping.

Detecting LDAP injection in Echo Go applications requires both static code analysis and dynamic scanning. The most effective approach combines middleBrick's automated scanning with manual code review of authentication and directory service integration points.

middleBrick's scanner specifically targets LDAP injection vulnerabilities through its Input Validation category. When scanning an Echo Go API endpoint that processes LDAP queries, middleBrick:

1. Identifies LDAP filter construction patterns in the application code
2. Tests for common LDAP injection payloads including wildcard operators, boolean operators, and meta-characters
3. Attempts authentication bypass by manipulating filter logic
4. Checks for information disclosure through LDAP error messages

The scanner tests with payloads like:

*)(uid=*
*))(|(uid=*
*)))(&(objectClass=*
*))(|(objectClass=inetOrgPerson)(objectClass=*

For Echo Go specifically, middleBrick's CLI tool can be integrated into your development workflow:

npx middlebrick scan https://your-echo-app.com/api/auth/login --category=InputValidation

This command scans the specified endpoint for LDAP injection vulnerabilities, returning a detailed report with severity levels and remediation guidance.

Manual detection in Echo Go code should focus on these patterns:

• Direct string concatenation with user input in LDAP filter construction
• Missing input validation before LDAP query execution
• Dynamic construction of filter strings using fmt.Sprintf or string concatenation
• Unescaped special LDAP characters (&, |, !, =, <, >, ~, *, (, ), /)

Echo Go's middleware structure makes it easy to audit LDAP usage. Search your codebase for:

grep -r "ldap\.NewSearchRequest" . --include="*.go"

Then examine each instance for direct user input usage in filter construction. Pay special attention to authentication middleware, user search endpoints, and any directory service integrations.

middleBrick's continuous monitoring feature (Pro plan) can automatically re-scan your Echo Go APIs on a schedule, alerting you to new LDAP injection vulnerabilities introduced during development or through third-party dependencies.

Remediating LDAP injection in Echo Go requires both input validation and proper LDAP filter construction. The most secure approach uses parameterized LDAP queries and strict input validation before any LDAP operation.

First, implement input validation middleware in Echo Go:

func validateLDAPInput(next echo.HandlerFunc) echo.HandlerFunc {
    return func(c echo.Context) error {
        // Validate username format
        username := c.FormValue("username")
        if !isValidLDAPIdentifier(username) {
            return echo.NewHTTPError(http.StatusBadRequest, "Invalid username format")
        }
        
        // Validate other parameters...
        return next(c)
    }
}

func isValidLDAPIdentifier(input string) bool {
    // Allow only alphanumeric, dot, hyphen, underscore
    matched, _ := regexp.MatchString(`^[a-zA-Z0-9._-]+$`, input)
    return matched && len(input) <= 255
}

Apply this middleware to routes that process LDAP queries:

e.POST("/api/auth/login", authenticate, validateLDAPInput)
e.POST("/api/users/search", searchUsers, validateLDAPInput)

For LDAP filter construction, use the ldap package's built-in escaping functions:

import "github.com/go-ldap/ldap/v3"

func authenticate(c echo.Context) error {
    username := c.FormValue("username")
    password := c.FormValue("password")
    
    // Properly escape LDAP special characters
    escapedUsername := ldap.EscapeFilter(username)
    
    filter := fmt.Sprintf("(uid=%s)", escapedUsername)
    
    searchRequest := ldap.NewSearchRequest(
        "dc=example,dc=com",
        ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false,
        filter,
        []string{"uid", "cn", "sn"},
        nil,
    )
    
    sr, err := connection.Search(searchRequest)
    if err != nil {
        return echo.NewHTTPError(http.StatusUnauthorized, "Authentication failed")
    }
    
    // Process results...
    return c.JSON(http.StatusOK, map[string]string{"status": "authenticated"})
}

The ldap.EscapeFilter function handles all special LDAP characters, preventing injection through filter manipulation.

For more complex queries, use the ldap.SearchRequest's Filter field with proper construction:

func searchUsers(c echo.Context) error {
    var params SearchParams
    if err := c.Bind(&params); err != nil {
        return err
    }
    
    // Validate and escape all inputs
    escapedUsername := ldap.EscapeFilter(params.Username)
    escapedDepartment := ldap.EscapeFilter(params.Department)
    
    // Construct filter using safe concatenation
    filter := fmt.Sprintf("(&(uid=%s)(department=%s))", 
        escapedUsername, escapedDepartment)
    
    searchRequest := ldap.NewSearchRequest(
        "ou=users,dc=example,dc=com",
        ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false,
        filter,
        []string{"dn", "uid", "cn"},
        nil,
    )
    
    sr, err := connection.Search(searchRequest)
    if err != nil {
        return echo.NewHTTPError(http.StatusInternalServerError, "Search failed")
    }
    
    return c.JSON(http.StatusOK, sr.Entries)
}

For authentication middleware, consider using a whitelist approach:

func LDAPAuthMiddleware(next echo.HandlerFunc) echo.HandlerFunc {
    return func(c echo.Context) error {
        token := c.Request().Header.Get("Authorization")
        
        // Validate token format before LDAP query
        if !isValidToken(token) {
            return echo.NewHTTPError(http.StatusUnauthorized, "Invalid token format")
        }
        
        escapedToken := ldap.EscapeFilter(token)
        filter := fmt.Sprintf("(token=%s)", escapedToken)
        
        searchRequest := ldap.NewSearchRequest(
            "ou=users,dc=example,dc=com",
            ldap.ScopeSingleLevel, ldap.NeverDerefAliases, 0, 0, false,
            filter,
            []string{"dn", "token"},
            nil,
        )
        
        // Search and validate...
        return next(c)
    }
}

middleBrick's Pro plan includes continuous monitoring that can alert you when LDAP injection vulnerabilities are introduced through code changes, helping maintain security as your Echo Go application evolves.