Jason,
First start with one of the RegEx in 10 minutes a day type books. I
think there is one from Sams Publishing. If you want to be a serious
geek, Regular Expressions by Jeffrey Friedl from O'Reilly rocks.
-dhs
Dean H. Saxe, CISSP, CEH
[EMAIL PROTECTED]
"If liberty means anything at all, it means the right to tell people
what they do not want to hear."
-- George Orwell, 1945
On Aug 10, 2006, at 10:58 AM, West, Jason wrote:
OT: Can you all suggest a good book that would give a better
understanding on regular expression programming?
Thanks
JLW
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Teddy
Payne
Sent: Monday, August 07, 2006 15:52
To: discussion@acfug.org
Subject: Re: re[2]: [ACFUG Discuss] Regex help
I think what Dean is suggesting here is that it is wiser to
validate both from the server and the client. The server
validation being more reliable than the client. This is a well
adopted paradigm and Dean helps us remember this.
Also, MITM = Man In The Middle, which is a type of attack that can
be used to attack a web site as a way to change data that would
alter the normal behavior of the application.
Dean is very security conscious through profession and paranoia,
which is not a bad thing. In the normal development process, it is
always recommended to consider ways that your application can be
altered.
For this given situation, one recommendation for removing the
ability to perform a SQL injection attack is to use the
<cfqueryparam> or <cfprocparam> tag when inserting data. These
tags will throw exceptions if the datatypes do not match.
If this topic is of interest to other people, we should have Dean
present application security again. I attended oen of his
presentation before at ACFUG and it was a good primer for many
types of attacks.
Cheers
On 8/7/06, Dean H. Saxe <[EMAIL PROTECTED]> wrote:
Say you want to find your string and its 10 to 12 characters in the
hexadecimal character set. You can validate your data with:
[A-F0-9]{10,12}
This will match any hexadecimal number with a minimum of 10 chars and
a maximum of 12. Its a positive way of doing data validation on your
string.
-dhs
Dean H. Saxe, CISSP, CEH
[EMAIL PROTECTED]
"If liberty means anything at all, it means the right to tell people
what they do not want to hear."
-- George Orwell, 1945
On Aug 7, 2006, at 2:30 PM, Mischa Uppelschoten ext 10 wrote:
> Thanks! The piece that I was missing was the not (^) :)
>
>
> Dean, this expression rereplace(mystring, "[^A-F0-9]", "", "all")
> filters out all the unwanted characters. What does "{min},{max}" do?
> Mischa.
>
>
>
>
>> actually he would need this:
>
> rereplace(string, "[^a-fA-F0-9]", "", all);
>
>
> On 8/7/06, Dean H. Saxe < [EMAIL PROTECTED]> wrote:
> rereplace(string, "[^A-F0-9]", "", all);
>
> But if you're trying to do data validation, why wouldn't you throw
> out any data that doesn't match the regex [A-F0-9]{min,max}?
>
> -dhs
>
>
> Dean H. Saxe, CISSP, CEH
> [EMAIL PROTECTED]
> "If liberty means anything at all, it means the right to tell people
> what they do not want to hear."
> -- George Orwell, 1945
>
>
> On Aug 7, 2006, at 12:29 PM, Mischa Uppelschoten ext 10 wrote:
>
>> I can figure out how to remove a number of disallowed characters
>> from a string, but what if I want to include only a-f and 0-9 and
>> discard everything else?
>>
>> so if a user supplies: E97152C6CF1DD198DE95C7F2C2EF5EA0, do nothing
>> if a user supplies E97152C6CF1DD198DE9;hackcode;
>>
>> it is supposed to return: E97152C6CF1DD198DE9accde
>>
>> Is that possible with a single regex? Or will I have to cycle
>> through the string, and replace every character that doesn't match
>> [a-f]|[0-9] with nothing?
>>
>> Thanks!
>> Mischa,
>>
>>
>>
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