🛡️ Sentinel: [HIGH] Fix Server-Side Request Forgery (SSRF) risk in plugin downloads

.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.
+## 2024-05-24 - SSRF vulnerability in plugin downloads
+**Vulnerability:** The application used `http.Get` directly for downloading plugins from potentially user-controlled URLs without IP validation, exposing it to Server-Side Request Forgery (SSRF) attacks, specifically against cloud metadata endpoints like `169.254.169.254`.
+**Learning:** `http.Get` does not protect against SSRF. Merely parsing URLs is insufficient since DNS rebinding can still target internal IPs.
+**Prevention:** Use a custom `http.Client` with a `net.Dialer` and a `Control` hook to intercept socket connections *after* DNS resolution but *before* connecting, blocking prohibited IPs (e.g., `169.254.169.254`). Also, ensure proper timeouts are configured.

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"
@@ -24,6 +26,27 @@ import (
 var metadataRegex = regexp.MustCompile(`^#\s*@(\w+[-\w]*)\s+(.+)$`)
 var versionRegex = regexp.MustCompile(`(?m)^#\s*@version\s+(.+)$`)
 
+func newSafeHTTPClient() *http.Client {
+	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 {
+				host = strings.SplitN(host, "%", 2)[0]
+				if ip := net.ParseIP(host); ip != nil && ip.String() == "169.254.169.254" {
+					return fmt.Errorf("blocked cloud metadata IP")
+				}
+			}
+			return nil
+		},
+	}
+	t := http.DefaultTransport.(*http.Transport).Clone()
+	t.DialContext = dialer.DialContext
+	t.DisableKeepAlives = true
+	return &http.Client{Timeout: 10 * time.Second, Transport: t}
+}
+
 // sanitizeFilename ensures a filename cannot be used for path traversal
 func sanitizeFilename(name string) string {
 	return filepath.Base(filepath.Clean("/" + name))
@@ -410,7 +433,8 @@ func (m *Manager) addScriptPlugin(owner, repo, pluginName string) error {
 
 	fmt.Printf("Fetching script from: %s\n", rawURL)
 
-	resp, err := http.Get(rawURL)
+	client := newSafeHTTPClient()
+	resp, err := client.Get(rawURL)
 	if err != nil {
 		return fmt.Errorf("failed to fetch plugin: %w", err)
 	}
@@ -468,7 +492,8 @@ func (m *Manager) addFromDirectURL(rawURL string) error {
 		return fmt.Errorf("unsupported URL scheme: %s", parsedURL.Scheme)
 	}
 
-	resp, err := http.Get(parsedURL.String())
+	client := newSafeHTTPClient()
+	resp, err := client.Get(parsedURL.String())
 	if err != nil {
 		return fmt.Errorf("failed to fetch plugin: %w", err)
 	}