Trusting Trust - Revision history

Jens at 16:04, 7 January 2005

2005-01-07T16:04:39Z

← Older revision		Revision as of 16:04, 7 January 2005
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	*check checksums of downloaded files		*check checksums of downloaded files
	===how-to===		===how-to===
	*most checksums are calculated with MD5 or ~~CRC32~~		*most checksums are calculated with MD5 or SHA1
	#you need a program to calculate checksums most unix based systems have md5sum installed windows systems don't have it, download one!		#you need a program to calculate checksums most unix based systems have md5sum installed windows systems don't have it, download one!
	#call md5sum/md5.exe filename and you'll get it's checksum		#call md5sum/md5.exe filename and you'll get it's checksum

2005-01-07T15:52:25Z

@@ Line 50: / Line 50: @@
 *If this program is compiled and executed it will produce it's own source code
-*If the source code is compiled it will create a program which will produce it’s own source code
+*If the source code is compiled it will create a program which will produce it's own source code
 *If the source code is compiled it will create
 *...
@@ Line 200: / Line 200: @@
 ==What can we do?==
 ==Links==

2005-01-07T15:47:06Z

← Older revision		Revision as of 15:47, 7 January 2005
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	}		}
	...		...

			*Did the first Compiler ever build have a Trojan horse?

			==Summary==

			*Moral: You can't trust code that you did not totally create yourself.
			*Trojan horses can be hidden not only on software level. They can be in your BIOS, the microcode of your hardware or even hardwired onto your devices...

	==What can we do?==		==What can we do?==

2005-01-07T15:45:57Z

@@ Line 151: / Line 151: @@
 ===Example 7===
 '''Inserting malicious content 3'''
  ...
@@ Line 169: / Line 168: @@
 ===Example 8===
 '''Finalizing the evil plan...'''
  ...

2005-01-07T14:14:06Z

← Older revision		Revision as of 14:14, 7 January 2005
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	...		...

			===Example 8===
			'''Finalizing the evil plan...'''
			*With this litte additional check we can find certain patterns and do something ''bad'' everytime we find them
			*We have constructed a Trojan Horse!
			*At this point we could look for the Unix login command and change a certain part (i.e. add a backdoor) every time the login command is compiled

			...
			int compile(char *s)
			{
			if(match(s, "pattern1"))
			{
			compile("bug1");
			return 1;
			}
			if(match(s, "pattern2"))
			{
			compile("bug2");
			return 1;
			}
			...
			}
			...

	==What can we do?==		==What can we do?==

2005-01-07T14:11:04Z

@@ Line 148: / Line 148: @@
+ }
  ...
 ==What can we do?==

2005-01-07T14:07:34Z

← Older revision		Revision as of 14:07, 7 January 2005
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	...		...

			*If we use this compiler as the new system compiler it will be able to compile example 3
			*The compiler has learned something!

			===Example 5===
			'''Inserting malicious content 1'''
			*Let's find another part of the compiler
			*We asume that compile() compiles the next line of the input file

			...
			int compile(char *s)
			{
			...
			}
			...

			===Example 6===
			'''Inserting malicious content 2'''
			*With this litte additional check we can find certain patterns and do something ''bad'' everytime we find them
			*We have constructed a Trojan Horse!
			*At this point we could look for the Unix login command and change a certain part (i.e. add a backdoor) every time the login command is compiled

			...
			int compile(char *s)
			{
			if(match(s, "pattern"))
			{
			compile("bug");
			return 1;
			}
			...
			}
			...

	==What can we do?==		==What can we do?==

2005-01-07T13:54:38Z

@@ Line 95: / Line 95: @@
  if(c == 'v')			//second character equals v
  	return('\v');		//escaped \v found
  ...

2005-01-07T13:41:19Z

← Older revision		Revision as of 13:41, 7 January 2005
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	==What can we do?==		==What can we do?==

			==Links==
	===Checksums===		===Checksums===
	[http://www.shen.myby.co.uk/threel/tech/tools/md5.htm MD5 for Win32]		[http://www.shen.myby.co.uk/threel/tech/tools/md5.htm MD5 for Win32]
			===Based on===
			[http://www.acm.org/classics/sep95/ Reflections on Trusting Trust by Ken Thompson]

2005-01-07T13:39:26Z

@@ Line 73: / Line 73: @@
  if(c == 'n')			//second character equals n
  	return('\n');		//escaped \n found
  ...