Banner Flaw

After playing around with the banner command to understand how it works, I discovered something. Did anyone notice the flaw in the banner command?

If you have the password configured for the console line, and you decided to set up a banner message with the banner exec command by doing what I did:

Router(config)#banner exec hello
Enter TEXT message. End with the character 'h'.
O I C How it works. hahahah
Router(config)#exit
Router#

You would get the "ello" string that will appear after you type in your password to log on the console. Imagine someone using a bad word as a delimiter instead of hello

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

thehourman

I believe they mentioned that in any book, I think. Whatever character you use after the exec, motd, will be the delimiting character.

rogue2shadow

thehourman wrote: »

I believe they mentioned that in any book, I think. Whatever character you use after the exec, motd, will be the delimiting character.

+1. Agreed.

hiddenknight821

That's not my point. I know we're suppose to use one delimiter character, but like I said I was playing around with the command, but I did not expect to see the string "ello" after entering the password for the console terminal. I think whoever developed the IOS left a bug. Did you guys actually try to experiment what I mentioned above? Please let me know if you see the same result.

gosh1976

Maybe I'm not following you but where's the bug? if i typed in that I would fully expect to see a banner that reads exactly:
ello
O I C How it works.

xenodamus

hiddenknight821 wrote: »

Router(config)#banner exec hello
Enter TEXT message. End with the character 'h'.
O I C How it works. hahahah
Router(config)#exit

When you type "banner exec" the next character you enter will be the delimiting character. In this case when you type "hello" it takes the "h" as the opening of your banner. Thus, "ello" is the first text to appear in the banner, with the banner ending the next time you type "h".

tiersten

What xenodamus said.