🛡️ Sentinel: [CRITICAL] Fix Server-Side Request Forgery (SSRF) vulnerabilities

.jules/sentinel.md

@@ -16,3 +16,7 @@
 **Vulnerability:** Writing fully buffered in-memory data to temporary disk files solely for parsing.
 **Learning:** This increases attack surface, risks disk exhaustion, and violates the principle of least privilege.
 **Prevention:** Refactor parsing functions to accept byte slices or `io.Reader` directly to process data in memory.
+## 2024-11-20 - SSRF Prevention with net.Dialer
+**Vulnerability:** Untrusted user-provided URLs could access cloud metadata endpoints via Server-Side Request Forgery (SSRF) because `http.Get()` was used without preventing IP resolution to known restricted IPs.
+**Learning:** Using a custom `net.Dialer` with a `Control` hook prevents SSRF by evaluating the resolved IP address *after* DNS resolution but *before* the socket connects. This stops DNS rebinding and IP obfuscation attacks.
+**Prevention:** Block specific cloud metadata IPs like `169.254.169.254` in the `Control` hook. Ensure IPv6 Zone Identifiers are stripped before parsing.

internal/plugin/manager.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"net/url"
 	"os"
@@ -16,6 +17,7 @@ import (
 	"runtime"
 	"sort"
 	"strings"
+	"syscall"
 	"time"
 
 	"github.com/himattm/prism/internal/fsutil"
@@ -410,7 +412,8 @@ func (m *Manager) addScriptPlugin(owner, repo, pluginName string) error {
 
 	fmt.Printf("Fetching script from: %s\n", rawURL)
 
-	resp, err := http.Get(rawURL)
+	client := newSafeClient(10 * time.Second)
+	resp, err := client.Get(rawURL)
 	if err != nil {
 		return fmt.Errorf("failed to fetch plugin: %w", err)
 	}
@@ -468,7 +471,8 @@ func (m *Manager) addFromDirectURL(rawURL string) error {
 		return fmt.Errorf("unsupported URL scheme: %s", parsedURL.Scheme)
 	}
 
-	resp, err := http.Get(parsedURL.String())
+	client := newSafeClient(10 * time.Second)
+	resp, err := client.Get(parsedURL.String())
 	if err != nil {
 		return fmt.Errorf("failed to fetch plugin: %w", err)
 	}
@@ -860,3 +864,31 @@ func CompareVersions(a, b string) int {
 
 	return 0
 }
+
+func newSafeClient(timeout time.Duration) *http.Client {
+	transport := http.DefaultTransport.(*http.Transport).Clone()
+	transport.DisableKeepAlives = true
+	dialer := &net.Dialer{
+		Timeout:   30 * time.Second,
+		KeepAlive: 30 * time.Second,
+		Control: func(network, address string, c syscall.RawConn) error {
+			host, _, err := net.SplitHostPort(address)
+			if err != nil {
+				return err
+			}
+			if idx := strings.IndexByte(host, '%'); idx != -1 {
+				host = host[:idx]
+			}
+			ip := net.ParseIP(host)
+			if ip != nil && ip.String() == "169.254.169.254" {
+				return fmt.Errorf("access to cloud metadata IP is forbidden")
+			}
+			return nil
+		},
+	}
+	transport.DialContext = dialer.DialContext
+	return &http.Client{
+		Timeout:   timeout,
+		Transport: transport,
+	}
+}