Architecture of a Proactive Security Tool

1. Architecture of a Proactive Security Tool Vivek Ramachandran

2. What does a proactive tool do? • Tool makes dynamic decisions at runtime based on information collected from the network. • “Sniff – decide – Inject” • The tool logically is divided into 3 parts: • The sniffer logic • The injection logic • The decision logic • These three communicate via some IPC mechanism e.g. pipes, message queues, shared memory • This is as cool a tool can get ! :D

3. Architecture of a Proactive Security Tool Ethernet Interface Decide Action (6) (5) Inject packets Send output of decision Sniff packets (3) Send inputs (4) Injector Sniffer Create Injector thread Create Sniffer thread Main() (2) (1)

4. Architecture of a Proactive Security Tool • Create sniffer thread • Create injector thread • Sniff packets from the network • Send inputs to the decision module • Send output of decision to injector • Inject packets • Goto step 3:

5. Architecture of a Proactive Security Tool Multi threaded programming • Create sniffer thread • Create injector thread • Sniff packets from the network • Send inputs to the decision module • Send output of decision to injector • Inject packets • Goto step 3:

6. Architecture of a Proactive Security Tool Raw Sockets • Create sniffer thread • Create injector thread • Sniff packets from the network • Send inputs to the decision module • Send output of decision to injector • Inject packets • Goto step 3:

7. Architecture of a Proactive Security Tool IPC – message queues • Create sniffer thread • Create injector thread • Sniff packets from the network • Send inputs to the decision module • Send output of decision to injector • Inject packets • Goto step 3:

8. Multithreading basics • Threads are light-weight processes • only local variables in a function are copied (e.g. each thread has its own stack) • most other data is shared between threads (e.g. global variables & the heap) • runs in parallel with the main thread • pthreads is the POSIX threads standard • pthread_create() is used to create a thread • Takes a function to execute as input • Takes an argument to pass to that function • pthread_join() is used by the parent to wait for daughter threads to finish execution • Visit http://www.llnl.gov/computing/tutorials/pthreads/ for a comprehensive tutorial

9. IPC – Message Queue basics • Message Queues are linked lists of messages maintained by the kernel • Processes are allowed to read and write messages from and to a message queue if they have requisite permissions • Allows for an asynchronous form of communication • For a comprehensive yet easy to understand tutorial visit http://beej.us/guide/ipc/mq.html

10. IPC – Message Queue basics • msgget() to create a message queue • Need to use ftok() to create the key • msgsnd() to send message into a queue • Message should be of format: struct message{ long mtype; // Mandatory char data[1]; …} • msgrcv() to receive a message from the queue

11. What tools will we make? • GenericTool.c : A tool which articulates the architecture discussed in this ppt • GenericTool-1.c: A modified version of the above to illustrate message transmission using message queues • ArpDos: A tool to illustrate the working of the above architecture. It does a denial of service on the network by replying to every Arp request it sees on the network

12. Let the games begin !!