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Xamarin

Hooking

Traffic Interception

Resources

The following is outdated, but I opted to keep it in the notes for reference: - How To Capture Non-Proxy Aware Mobile Application Traffic (IOS & Android) Xamarin/Flutter -Pentesting | by salman syed | Medium More on IP tables at: - iptables Demystified - Port Redirection and Forwarding HTTP Traffic to another machine (part 1) - YouTube

Steps

  1. Follow the steps in the How To Capture Non-Proxy Aware Mobile Application Traffic (IOS & Android) Xamarin/Flutter -Pentesting | by salman syed | Medium blog to set up OpenVPN.

    Ensure OpenVPN is set to use TCP

  2. Delete all iptable rules, refer to iptables(8) - Linux man page (die.net) for full context. 
    # Flush filter rules i.e: FOWARD, INPUT, OUTPUT
iptables -F

# Allow all inbound traffic
sudo iptables -P INPUT ACCEPT
sudo iptables -P OUTPUT ACCEPT
sudo iptables -P FORWARD ACCEPT

# [optional] Get NAT rule number
sudo iptables -t nat -v -L -n --line-number

# [optional] Flush nat rule i.e: PREROUTING, POSTROUTING
sudo iptables -t nat -D PREROUTING <rule_number>
  3. Route traffic from your VPN interface and redirect to your host (Burp Suite) 
    # To forward to local port 8888 
iptables -t nat -A PREROUTING -i tun0 -p tcp --dport 443 -j REDIRECT --to-port 8888 

# [optional] if you delete OpenVPN's NATing rule by accident, restore it with
sudo iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o ens33 -j MASQUERADE # , where ens33 is the interface connected to the internet
  4. Enable IP Forwarding 
    # Enable
sysctl -w net.ipv4.ip_forward=1

# [optional] Validate it works
cat /proc/sys/net/ipv4/ip_forward

    If you don't see traffic in Burp, checkout Burp's Dashboard - sometimes it's an SSL pinning issue.

Bypass SSL pinning