Prevent man-in-the-middle attacks

Cargo.lock

@@ -95,6 +95,12 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "autocfg"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d49d90015b3c36167a20fe2810c5cd875ad504b39cff3d4eae7977e6b7c1cb2"
+
 [[package]]
 name = "autocfg"
 version = "1.0.1"
@@ -271,6 +277,12 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "const-oid"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d6f2aa4d0537bcc1c74df8755072bd31c1ef1a3a1b85a68e8404a8c353b7b8b"
+
 [[package]]
 name = "core-foundation"
 version = "0.9.2"
@@ -341,6 +353,17 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "crypto-bigint"
+version = "0.2.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f83bd3bb4314701c568e340cd8cf78c975aa0ca79e03d3f6d1677d5b0c9c0c03"
+dependencies = [
+ "generic-array",
+ "rand_core",
+ "subtle",
+]
+
 [[package]]
 name = "crypto-common"
 version = "0.1.1"
@@ -438,6 +461,16 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "der"
+version = "0.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "79b71cca7d95d7681a4b3b9cdf63c8dbc3730d0584c2c74e31416d64a90493f4"
+dependencies = [
+ "const-oid",
+ "crypto-bigint",
+]
+
 [[package]]
 name = "digest"
 version = "0.9.0"
@@ -1104,7 +1137,7 @@ version = "1.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282a6247722caba404c065016bbfa522806e51714c34f5dfc3e4a3a46fcb4223"
 dependencies = [
- "autocfg",
+ "autocfg 1.0.1",
  "hashbrown",
 ]
 
@@ -1219,6 +1252,9 @@ name = "lazy_static"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+dependencies = [
+ "spin",
+]
 
 [[package]]
 name = "lazycell"
@@ -1429,6 +1465,7 @@ dependencies = [
  "protobuf",
  "quick-xml",
  "rand",
+ "rsa",
  "serde",
  "serde_json",
  "sha-1 0.10.0",
@@ -1595,7 +1632,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a92518e98c078586bc6c934028adcca4c92a53d6a958196de835170a01d84e4b"
 dependencies = [
  "adler",
- "autocfg",
+ "autocfg 1.0.1",
 ]
 
 [[package]]
@@ -1780,12 +1817,30 @@ version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f93ab6289c7b344a8a9f60f88d80aa20032336fe78da341afc91c8a2341fc75f"
 dependencies = [
- "autocfg",
+ "autocfg 1.0.1",
  "num-integer",
  "num-traits",
  "rand",
 ]
 
+[[package]]
+name = "num-bigint-dig"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4547ee5541c18742396ae2c895d0717d0f886d8823b8399cdaf7b07d63ad0480"
+dependencies = [
+ "autocfg 0.1.7",
+ "byteorder",
+ "lazy_static",
+ "libm",
+ "num-integer",
+ "num-iter",
+ "num-traits",
+ "rand",
+ "smallvec",
+ "zeroize",
+]
+
 [[package]]
 name = "num-complex"
 version = "0.4.0"
@@ -1812,7 +1867,7 @@ version = "0.1.44"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d2cc698a63b549a70bc047073d2949cce27cd1c7b0a4a862d08a8031bc2801db"
 dependencies = [
- "autocfg",
+ "autocfg 1.0.1",
  "num-traits",
 ]
 
@@ -1822,7 +1877,7 @@ version = "0.1.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b2021c8337a54d21aca0d59a92577a029af9431cb59b909b03252b9c164fad59"
 dependencies = [
- "autocfg",
+ "autocfg 1.0.1",
  "num-integer",
  "num-traits",
 ]
@@ -1833,7 +1888,7 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d41702bd167c2df5520b384281bc111a4b5efcf7fbc4c9c222c815b07e0a6a6a"
 dependencies = [
- "autocfg",
+ "autocfg 1.0.1",
  "num-bigint",
  "num-integer",
  "num-traits",
@@ -1845,7 +1900,7 @@ version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a64b1ec5cda2586e284722486d802acf1f7dbdc623e2bfc57e65ca1cd099290"
 dependencies = [
- "autocfg",
+ "autocfg 1.0.1",
  "libm",
 ]
 
@@ -2026,6 +2081,28 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
+[[package]]
+name = "pkcs1"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "116bee8279d783c0cf370efa1a94632f2108e5ef0bb32df31f051647810a4e2c"
+dependencies = [
+ "der",
+ "zeroize",
+]
+
+[[package]]
+name = "pkcs8"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee3ef9b64d26bad0536099c816c6734379e45bbd5f14798def6809e5cc350447"
+dependencies = [
+ "der",
+ "pkcs1",
+ "spki",
+ "zeroize",
+]
+
 [[package]]
 name = "pkg-config"
 version = "0.3.24"
@@ -2071,7 +2148,7 @@ version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "00ba480ac08d3cfc40dea10fd466fd2c14dee3ea6fc7873bc4079eda2727caf0"
 dependencies = [
- "autocfg",
+ "autocfg 1.0.1",
  "indexmap",
 ]
 
@@ -2290,6 +2367,26 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "rsa"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e05c2603e2823634ab331437001b411b9ed11660fbc4066f3908c84a9439260d"
+dependencies = [
+ "byteorder",
+ "digest 0.9.0",
+ "lazy_static",
+ "num-bigint-dig",
+ "num-integer",
+ "num-iter",
+ "num-traits",
+ "pkcs1",
+ "pkcs8",
+ "rand",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "rustc-demangle"
 version = "0.1.21"
@@ -2576,6 +2673,15 @@ version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
 
+[[package]]
+name = "spki"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c01a0c15da1b0b0e1494112e7af814a678fec9bd157881b49beac661e9b6f32"
+dependencies = [
+ "der",
+]
+
 [[package]]
 name = "stdweb"
 version = "0.1.3"
@@ -3262,3 +3368,24 @@ dependencies = [
  "syn",
  "synstructure",
 ]
+
+[[package]]
+name = "zeroize"
+version = "1.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d68d9dcec5f9b43a30d38c49f91dfedfaac384cb8f085faca366c26207dd1619"
+dependencies = [
+ "zeroize_derive",
+]
+
+[[package]]
+name = "zeroize_derive"
+version = "1.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "81e8f13fef10b63c06356d65d416b070798ddabcadc10d3ece0c5be9b3c7eddb"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "synstructure",
+]

core/Cargo.toml

@@ -40,6 +40,7 @@ priority-queue = "1.2.1"
 protobuf = "2"
 quick-xml = { version = "0.22", features = ["serialize"] }
 rand = "0.8"
+rsa = { version = "0.5", default-features = false, features = ["alloc"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 sha-1 = "0.10"

core/src/connection/handshake.rs

@@ -4,7 +4,8 @@ use byteorder::{BigEndian, ByteOrder, WriteBytesExt};
 use hmac::{Hmac, Mac};
 use protobuf::{self, Message};
 use rand::{thread_rng, RngCore};
-use sha1::Sha1;
+use rsa::{BigUint, PublicKey};
+use sha1::{Digest, Sha1};
 use thiserror::Error;
 use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
 use tokio_util::codec::{Decoder, Framed};
@@ -18,10 +19,31 @@ use crate::protocol::keyexchange::{
     APResponseMessage, ClientHello, ClientResponsePlaintext, Platform, ProductFlags,
 };
 
+const SERVER_KEY: [u8; 256] = [
+    0xac, 0xe0, 0x46, 0x0b, 0xff, 0xc2, 0x30, 0xaf, 0xf4, 0x6b, 0xfe, 0xc3, 0xbf, 0xbf, 0x86, 0x3d,
+    0xa1, 0x91, 0xc6, 0xcc, 0x33, 0x6c, 0x93, 0xa1, 0x4f, 0xb3, 0xb0, 0x16, 0x12, 0xac, 0xac, 0x6a,
+    0xf1, 0x80, 0xe7, 0xf6, 0x14, 0xd9, 0x42, 0x9d, 0xbe, 0x2e, 0x34, 0x66, 0x43, 0xe3, 0x62, 0xd2,
+    0x32, 0x7a, 0x1a, 0x0d, 0x92, 0x3b, 0xae, 0xdd, 0x14, 0x02, 0xb1, 0x81, 0x55, 0x05, 0x61, 0x04,
+    0xd5, 0x2c, 0x96, 0xa4, 0x4c, 0x1e, 0xcc, 0x02, 0x4a, 0xd4, 0xb2, 0x0c, 0x00, 0x1f, 0x17, 0xed,
+    0xc2, 0x2f, 0xc4, 0x35, 0x21, 0xc8, 0xf0, 0xcb, 0xae, 0xd2, 0xad, 0xd7, 0x2b, 0x0f, 0x9d, 0xb3,
+    0xc5, 0x32, 0x1a, 0x2a, 0xfe, 0x59, 0xf3, 0x5a, 0x0d, 0xac, 0x68, 0xf1, 0xfa, 0x62, 0x1e, 0xfb,
+    0x2c, 0x8d, 0x0c, 0xb7, 0x39, 0x2d, 0x92, 0x47, 0xe3, 0xd7, 0x35, 0x1a, 0x6d, 0xbd, 0x24, 0xc2,
+    0xae, 0x25, 0x5b, 0x88, 0xff, 0xab, 0x73, 0x29, 0x8a, 0x0b, 0xcc, 0xcd, 0x0c, 0x58, 0x67, 0x31,
+    0x89, 0xe8, 0xbd, 0x34, 0x80, 0x78, 0x4a, 0x5f, 0xc9, 0x6b, 0x89, 0x9d, 0x95, 0x6b, 0xfc, 0x86,
+    0xd7, 0x4f, 0x33, 0xa6, 0x78, 0x17, 0x96, 0xc9, 0xc3, 0x2d, 0x0d, 0x32, 0xa5, 0xab, 0xcd, 0x05,
+    0x27, 0xe2, 0xf7, 0x10, 0xa3, 0x96, 0x13, 0xc4, 0x2f, 0x99, 0xc0, 0x27, 0xbf, 0xed, 0x04, 0x9c,
+    0x3c, 0x27, 0x58, 0x04, 0xb6, 0xb2, 0x19, 0xf9, 0xc1, 0x2f, 0x02, 0xe9, 0x48, 0x63, 0xec, 0xa1,
+    0xb6, 0x42, 0xa0, 0x9d, 0x48, 0x25, 0xf8, 0xb3, 0x9d, 0xd0, 0xe8, 0x6a, 0xf9, 0x48, 0x4d, 0xa1,
+    0xc2, 0xba, 0x86, 0x30, 0x42, 0xea, 0x9d, 0xb3, 0x08, 0x6c, 0x19, 0x0e, 0x48, 0xb3, 0x9d, 0x66,
+    0xeb, 0x00, 0x06, 0xa2, 0x5a, 0xee, 0xa1, 0x1b, 0x13, 0x87, 0x3c, 0xd7, 0x19, 0xe6, 0x55, 0xbd,
+];
+
 #[derive(Debug, Error)]
 pub enum HandshakeError {
     #[error("invalid key length")]
     InvalidLength,
+    #[error("server key verification failed")]
+    VerificationFailed,
 }
 
 pub async fn handshake<T: AsyncRead + AsyncWrite + Unpin>(
@@ -37,7 +59,35 @@ pub async fn handshake<T: AsyncRead + AsyncWrite + Unpin>(
         .get_diffie_hellman()
         .get_gs()
         .to_owned();
+    let remote_signature = message
+        .get_challenge()
+        .get_login_crypto_challenge()
+        .get_diffie_hellman()
+        .get_gs_signature()
+        .to_owned();
 
+    // Prevent man-in-the-middle attacks: check server signature
+    let n = BigUint::from_bytes_be(&SERVER_KEY);
+    let e = BigUint::new(vec![65537]);
+    let public_key = rsa::RsaPublicKey::new(n, e).map_err(|_| {
+        io::Error::new(
+            io::ErrorKind::InvalidData,
+            HandshakeError::VerificationFailed,
+        )
+    })?;
+
+    let hash = Sha1::digest(&remote_key);
+    let padding = rsa::padding::PaddingScheme::new_pkcs1v15_sign(Some(rsa::hash::Hash::SHA1));
+    public_key
+        .verify(padding, &hash, &remote_signature)
+        .map_err(|_| {
+            io::Error::new(
+                io::ErrorKind::InvalidData,
+                HandshakeError::VerificationFailed,
+            )
+        })?;
+
+    // OK to proceed
     let shared_secret = local_keys.shared_secret(&remote_key);
     let (challenge, send_key, recv_key) = compute_keys(&shared_secret, &accumulator)?;
     let codec = ApCodec::new(&send_key, &recv_key);