Implement test for audit ticket MUL-02-002 WP2

Author: MarkusPettersson98

test/connection-checker/src/net.rs

@@ -7,6 +7,8 @@ use std::{
 
 use crate::cli::Opt;
 
+const PAYLOAD: &[u8] = b"Hello there!";
+
 pub fn send_tcp(opt: &Opt, destination: SocketAddr) -> eyre::Result<()> {
     let bind_addr: SocketAddr = SocketAddr::new(Ipv4Addr::new(0, 0, 0, 0).into(), 0);
 
@@ -31,7 +33,7 @@ pub fn send_tcp(opt: &Opt, destination: SocketAddr) -> eyre::Result<()> {
 
     let mut stream = std::net::TcpStream::from(sock);
     stream
-        .write_all(b"hello there")
+        .write_all(PAYLOAD)
         .wrap_err(eyre!("Failed to send message to {destination}"))?;
 
     Ok(())
@@ -56,7 +58,7 @@ pub fn send_udp(_opt: &Opt, destination: SocketAddr) -> Result<(), eyre::Error>
 
     let std_socket = std::net::UdpSocket::from(sock);
     std_socket
-        .send_to(b"Hello there!", destination)
+        .send_to(PAYLOAD, destination)
         .wrap_err(eyre!("Failed to send message to {destination}"))?;
 
     Ok(())

test/test-manager/src/network_monitor.rs

@@ -26,6 +26,7 @@ pub struct ParsedPacket {
     pub source: SocketAddr,
     pub destination: SocketAddr,
     pub protocol: IpNextHeaderProtocol,
+    pub payload: Vec<u8>,
 }
 
 impl PacketCodec for Codec {
@@ -75,9 +76,9 @@ impl Codec {
 
         let mut source = SocketAddr::new(IpAddr::V4(packet.get_source()), 0);
         let mut destination = SocketAddr::new(IpAddr::V4(packet.get_destination()), 0);
+        let mut payload = vec![];
 
         let protocol = packet.get_next_level_protocol();
-
         match protocol {
             IpHeaderProtocols::Tcp => {
                 let seg = TcpPacket::new(packet.payload()).or_else(|| {
@@ -86,6 +87,7 @@ impl Codec {
                 })?;
                 source.set_port(seg.get_source());
                 destination.set_port(seg.get_destination());
+                payload = seg.payload().to_vec();
             }
             IpHeaderProtocols::Udp => {
                 let seg = UdpPacket::new(packet.payload()).or_else(|| {
@@ -94,6 +96,7 @@ impl Codec {
                 })?;
                 source.set_port(seg.get_source());
                 destination.set_port(seg.get_destination());
+                payload = seg.payload().to_vec();
             }
             IpHeaderProtocols::Icmp => {}
             proto => log::debug!("ignoring v4 packet, transport/protocol type {proto}"),
@@ -103,6 +106,7 @@ impl Codec {
             source,
             destination,
             protocol,
+            payload,
         })
     }
 
@@ -114,6 +118,7 @@ impl Codec {
 
         let mut source = SocketAddr::new(IpAddr::V6(packet.get_source()), 0);
         let mut destination = SocketAddr::new(IpAddr::V6(packet.get_destination()), 0);
+        let mut payload = vec![];
 
         let protocol = packet.get_next_header();
         match protocol {
@@ -124,6 +129,7 @@ impl Codec {
                 })?;
                 source.set_port(seg.get_source());
                 destination.set_port(seg.get_destination());
+                payload = seg.payload().to_vec();
             }
             IpHeaderProtocols::Udp => {
                 let seg = UdpPacket::new(packet.payload()).or_else(|| {
@@ -132,6 +138,7 @@ impl Codec {
                 })?;
                 source.set_port(seg.get_source());
                 destination.set_port(seg.get_destination());
+                payload = seg.payload().to_vec();
             }
             IpHeaderProtocols::Icmpv6 => {}
             proto => log::debug!("ignoring v6 packet, transport/protocol type {proto}"),
@@ -141,6 +148,7 @@ impl Codec {
             source,
             destination,
             protocol,
+            payload,
         })
     }
 }

test/test-manager/src/tests/install.rs

@@ -287,6 +287,7 @@ pub async fn test_installation_idempotency(
     // Connect to any relay. This forces the daemon to enter a secured target state
     connect_and_wait(&mut mullvad_client)
         .await
+        .map(|_| ()) // Discard the new tunnel state
         .or_else(|error| match error {
             Error::UnexpectedErrorState(_) => Ok(()),
             err => Err(err),

test/test-manager/src/tests/tunnel.rs

@@ -2,11 +2,13 @@ use super::helpers::{
     self, connect_and_wait, disconnect_and_wait, set_bridge_settings, set_relay_settings,
 };
 use super::{config::TEST_CONFIG, Error, TestContext};
-use crate::network_monitor::{start_packet_monitor, MonitorOptions};
+use crate::network_monitor::{start_packet_monitor, MonitorOptions, ParsedPacket};
 use crate::tests::helpers::{login_with_retries, ConnChecker};
 
+use anyhow::{bail, ensure};
 use mullvad_management_interface::MullvadProxyClient;
 use mullvad_relay_selector::query::builder::RelayQueryBuilder;
+use mullvad_types::states::TunnelState;
 use mullvad_types::{
     constraints::Constraint,
     relay_constraints::{
@@ -802,3 +804,89 @@ pub async fn test_establish_tunnel_without_api(
     // Profit
     Ok(())
 }
+
+/// Fail to leak traffic to verify that mitigation for MUL-02-002-WP2
+/// ("Firewall allows deanonymization by eavesdropper") works.
+///
+/// # Vulnerability
+/// 1. Connect to a relay on port 443. Record this relay's IP address (the new gateway of the client)
+/// 2. Start listening for unencrypted traffic on the outbound network interface
+/// (Choose some human-readable, identifiable payload to look for in the outgoing TCP packets)
+/// 3. Start a rogue program which performs a GET request* containing the payload defined in step 2
+/// 4. The network snooper started in step 2 should now be able to observe the network request
+///    containing the identifiable payload being sent unencrypted over the wire
+///
+/// * or something similiar, as long as it generates some traffic containing UDP and/or TCP packets
+/// with the correct payload.
+#[test_function]
+pub async fn test_mul_02_002(
+    _: TestContext,
+    rpc: ServiceClient,
+    mut mullvad_client: MullvadProxyClient,
+) -> Result<(), anyhow::Error> {
+    // Step 0 - Disconnect from any active tunnel connection
+    helpers::disconnect_and_wait(&mut mullvad_client).await?;
+    // Step 1 - Choose a relay
+    let relay_constraints = RelayQueryBuilder::new()
+        .openvpn()
+        .transport_protocol(TransportProtocol::Tcp)
+        .port(443)
+        .into_constraint();
+
+    set_relay_settings(
+        &mut mullvad_client,
+        RelaySettings::Normal(relay_constraints),
+    )
+    .await?;
+
+    // Step 1.5 - Temporarily connect to the relay to get the target endpoint
+    let tunnel_state = helpers::connect_and_wait(&mut mullvad_client).await?;
+    let TunnelState::Connected { endpoint, .. } = tunnel_state else {
+        bail!("Expected tunnel state to be `Connected` - instead it was {tunnel_state:?}");
+    };
+    helpers::disconnect_and_wait(&mut mullvad_client).await?;
+    let gateway = endpoint.endpoint.address;
+
+    // Step 2 - Start a network monitor snooping the outbound network interface for some
+    // identifiable payload
+    // FIXME: This needs to be kept in sync with the magic payload string defined in `connection_cheker::net`.
+    // An easy fix would be to make the payload for `ConnCheck` configurable.
+    let unique_identifier = b"Hello there!";
+    let identify_rogue_packet = move |packet: &ParsedPacket| {
+        packet
+            .payload
+            .windows(unique_identifier.len())
+            .any(|window| window == unique_identifier)
+    };
+    let rogue_packet_monitor =
+        start_packet_monitor(identify_rogue_packet, MonitorOptions::default()).await;
+
+    // Step 3 - Start the rogue program which will try to leak traffic to the chosen relay endpoint
+    let mut checker = ConnChecker::new(rpc.clone(), mullvad_client.clone(), gateway);
+    let mut conn_artist = checker.spawn().await?;
+    // Before proceeding, assert that the method of detecting identifiable packets work.
+    conn_artist.check_connection().await?;
+    let monitor_result = rogue_packet_monitor.into_result().await.unwrap();
+
+    log::info!("Checking that the identifiable payload was detectable without encryption");
+    ensure!(
+        !monitor_result.packets.is_empty(),
+        "Did not observe rogue packets! The method seems to be broken"
+    );
+
+    // Step 4 - Finally, connect to a tunnel and assert that no outgoing traffic contains the
+    // payload in plain text.
+    helpers::connect_and_wait(&mut mullvad_client).await?;
+    let rogue_packet_monitor =
+        start_packet_monitor(identify_rogue_packet, MonitorOptions::default()).await;
+    conn_artist.check_connection().await?;
+    let monitor_result = rogue_packet_monitor.into_result().await.unwrap();
+
+    log::info!("Checking that the identifiable payload was not detected");
+    ensure!(
+        monitor_result.packets.is_empty(),
+        "Observed rogue packets! The tunnel seems to be leaking traffic"
+    );
+
+    Ok(())
+}