SystemsSec 2018W Lecture 11 - Revision history

Soma at 18:15, 14 February 2018

2018-02-14T18:15:36Z

← Older revision		Revision as of 18:15, 14 February 2018
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	==Audio==		==Audio==

	[https://homeostasis.scs.carleton.ca/~soma/systemssec-2018w/lectures/comp4108-2018w-lec11-~~12Feb2017~~.m4a Lecture 11 Audio]		[https://homeostasis.scs.carleton.ca/~soma/systemssec-2018w/lectures/comp4108-2018w-lec11-12Feb2018.m4a Lecture 11 Audio]

	==Notes==		==Notes==

Yannick: /* Notes */

2018-02-14T15:07:57Z

Notes

← Older revision		Revision as of 15:07, 14 February 2018
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	==Notes==		==Notes==
	HTTPS		=== HTTPS ===
	How to set it up?		- How to set it up?
	Get your public/private key pair signed by a respected authority		- Get your public/private key pair signed by a respected authority
	You can also self-sign but may encounter errors		- You can also self-sign but may encounter errors

	Current certificate is expired (Feb 2014)		- Current certificate is expired (Feb 2014)

	Need to get new certificate		- Need to get new certificate
	New thing called “Let’s encrypt” that offers free certificates (only for 90 days)		- New thing called “Let’s encrypt” that offers free certificates (only for 90 days)
	Recommends downloading CertBot		- Recommends downloading CertBot
	Might already come with Linux distribution		- Might already come with Linux distribution

	Certbot		=== Certbot ===
	Default commands provide useful instructions		- Default commands provide useful instructions
	Need to enter the webroot and url		- Need to enter the webroot and url
	This is to prove to Certbot that we have control of the server		- This is to prove to Certbot that we have control of the server
	Used to generate challenges that Certbot will verify		- Used to generate challenges that Certbot will verify

	Update the server’s configuration file with the newly generated certificates		- Update the server’s configuration file with the newly generated certificates
	In this case used symbolic links		- In this case used symbolic links
	Restart the server		- Restart the server



	Buffer overflows		=== Buffer overflows===
	Make a classic C program		- Make a classic C program
	Typing over the buffer length		- Typing over the buffer length
	Detected stack smashing		- Detected stack smashing
	ONLY after writing and reading the bytes		- ONLY after writing and reading the bytes
	Use of canary words to detect if stack has been modified		- Use of canary words to detect if stack has been modified
	If you were a real attacker you would try and target a buffer that wasn’t protected by it		- If you were a real attacker you would try and target a buffer that wasn’t protected by it
	The heap is a prime target		- The heap is a prime target
	If we turn off the stack protection		- If we turn off the stack protection
	Received a SIGSEGV from the kernel and the core is dumped		- Received a SIGSEGV from the kernel and the core is dumped
	Kernel saying that you tried to access memory that was not given		- Kernel saying that you tried to access memory that was not given
	Process can intercept signal and choose to do something with it		- Process can intercept signal and choose to do something with it
	Default handler causes you to crash with segfault		- Default handler causes you to crash with segfault
	What is “core dumped”?		- What is “core dumped”?
	Comes from core memory		- Comes from core memory
	Means that it’s written memory out		- Means that it’s written memory out

	Modify C program to have a function called target in the binary but it’s never called. Goal is to make the code jump to the target function and execute.		Modify C program to have a function called target in the binary but it’s never called. Goal is to make the code jump to the target function and execute.

Yannick: /* Notes */

2018-02-14T15:05:27Z

Notes

← Older revision		Revision as of 15:05, 14 February 2018
Line 4:		Line 4:

	==Notes==		==Notes==
			HTTPS
			How to set it up?
			Get your public/private key pair signed by a respected authority
			You can also self-sign but may encounter errors

			Current certificate is expired (Feb 2014)

			Need to get new certificate
			New thing called “Let’s encrypt” that offers free certificates (only for 90 days)
			Recommends downloading CertBot
			Might already come with Linux distribution

			Certbot
			Default commands provide useful instructions
			Need to enter the webroot and url
			This is to prove to Certbot that we have control of the server
			Used to generate challenges that Certbot will verify

			Update the server’s configuration file with the newly generated certificates
			In this case used symbolic links
			Restart the server



			Buffer overflows
			Make a classic C program
			Typing over the buffer length
			Detected stack smashing
			ONLY after writing and reading the bytes
			Use of canary words to detect if stack has been modified
			If you were a real attacker you would try and target a buffer that wasn’t protected by it
			The heap is a prime target
			If we turn off the stack protection
			Received a SIGSEGV from the kernel and the core is dumped
			Kernel saying that you tried to access memory that was not given
			Process can intercept signal and choose to do something with it
			Default handler causes you to crash with segfault
			What is “core dumped”?
			Comes from core memory
			Means that it’s written memory out

			Modify C program to have a function called target in the binary but it’s never called. Goal is to make the code jump to the target function and execute.
			What tools can we use?
			GDB to figure out what’s happening with memory

			“Stack Smashing for Fun and Profit”
			Basic idea is you find the address and then overwrite the address
			Might have to turn off address space randomization

Soma: Created page with "==Audio== [https://homeostasis.scs.carleton.ca/~soma/systemssec-2018w/lectures/comp4108-2018w-lec11-12Feb2017.m4a Lecture 11 Audio] ==Notes=="

2018-02-12T17:25:27Z

Created page with "==Audio== [https://homeostasis.scs.carleton.ca/~soma/systemssec-2018w/lectures/comp4108-2018w-lec11-12Feb2017.m4a Lecture 11 Audio] ==Notes=="

New page

==Audio==

[https://homeostasis.scs.carleton.ca/~soma/systemssec-2018w/lectures/comp4108-2018w-lec11-12Feb2017.m4a Lecture 11 Audio]

==Notes==