Fix Broken User Authentication in Actix Web

Broken authentication is the gateway for account takeovers and credential stuffing. In the Actix Web ecosystem, this usually stems from manual session management, plaintext password comparisons, or failing to set secure cookie attributes. If you aren't using a cryptographically secure session middleware and a robust KDF like Argon2, your app is basically an open door.

The Vulnerable Pattern

use actix_web::{post, web, HttpResponse, cookie::Cookie};
#[post(“/login”)]
async fn login(form: web::Form) -> HttpResponse {
// VULNERABILITY: Plaintext password comparison
if form.username == “admin” && form.password == “p@ssword123” {
// VULNERABILITY: Insecure cookie (no HttpOnly, no Secure flags, predictable value)
return HttpResponse::Ok()
.cookie(Cookie::new(“auth”, “admin_session”))
.finish();
}
HttpResponse::Unauthorized().finish()
}

The Secure Implementation

The vulnerable code is a disaster: it compares passwords in plaintext, making it susceptible to timing attacks and database leaks, and issues a raw cookie lacking 'HttpOnly' and 'Secure' flags, making it trivial to steal via XSS. The secure implementation uses 'Argon2' to verify hashes, preventing leakage. It leverages 'actix-session' (configured with a secure Key) to handle encrypted, server-side or signed client-side sessions automatically. Crucially, 'session.renew()' is called upon login to rotate the session ID, neutralizing session fixation attacks.

use actix_web::{post, web, HttpResponse};
use actix_session::Session;
use argon2::{password_hash::{PasswordHash, PasswordVerifier}, Argon2};
#[post(“/login”)]
async fn login(form: web::Form, session: Session, db: web::Data) -> HttpResponse {
let user_record = db.find_user(&form.username).await.unwrap();
let parsed_hash = PasswordHash::new(&user_record.password_hash).expect(“Invalid hash format”);
// FIX: Use Argon2 for secure password verification
if Argon2::default().verify_password(form.password.as_bytes(), &parsed_hash).is_ok() {
    // FIX: Use actix-session for encrypted, signed session management
    session.insert("user_id", user_record.id).expect("Session failure");
    // FIX: Prevent Session Fixation by renewing the session ID
    session.renew();
    return HttpResponse::Ok().finish();
}

HttpResponse::Unauthorized().finish()
}

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The Vulnerable Pattern

The Secure Implementation

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Verified by Ghost Labs Security Team