Revel's 'batteries-included' philosophy is a liability if you don't strip the training wheels before deployment. Default configurations often ship in 'dev' mode, which leaks stack traces and environment variables via the 'Panic Filter'. Furthermore, failing to enforce TLS and Secure/HttpOnly flags on session cookies allows for trivial session hijacking and MITM attacks.

The Vulnerable Pattern

[dev]
mode.dev = true
results.pretty = true
watch = true
Insecure Session Configuration
cookie.prefix = REVEL
cookie.secure = false
Missing explicit security headers
No HSTS, No X-Frame-Options

The Secure Implementation

To harden Revel, first kill 'mode.dev' to disable the interactive debugger and verbose error pages which are a goldmine for reconnaissance. Set 'cookie.secure = true' to ensure session tokens are only transmitted over HTTPS, and 'cookie.httponly = true' to prevent JavaScript-based exfiltration via XSS. The '__Host-' prefix on the cookie name adds an extra layer of protection against sub-domain shadowing. Finally, ensure the 'revel.SecurityFilter' is active in your filter chain (init.go) to automatically inject X-Content-Type-Options, X-Frame-Options, and X-XSS-Protection headers into every response.

[prod]
mode.dev = false
results.pretty = false
watch = false
Hardened Session Configuration
cookie.prefix = __Host-REVEL
cookie.secure = true
cookie.httponly = true
session.expires = 24h
Network Hardening
http.ssl = true
http.sslcert = /etc/ssl/certs/app.crt
http.sslkey = /etc/ssl/private/app.key
Ensure revel.Filters includes revel.SecurityFilter in init.go