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  1.  Home
  2. RPG400-L
  3. August 2011

RE: Reduce large amount of logicals in SUBFL pgm, take in another direction

Rory,

Agreed. Something can always be abused by someone. How you decide to
check a process' variables is a matter of choice. Some wish to check
for valid fields in an incoming SQL string others chose to allow SQL to
fail. Which methodology is better is a matter of opinion. Never
checking is a BAD idea IMHO.

Thanks for the input.

Gary


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Rory Hewitt
Sent: Monday, August 01, 2011 1:09 PM
To: RPG programming on the IBM i / System i
Subject: Re: Reduce large amount of logicals in SUBFL pgm,take in
another direction

Gary,

I think my previous email explained the reason used by Charles and
myself, but to emphasize:

It's not *your* code that's the problem - you may have designed it so
that user-entered values are valididated and you may have all kinds of
processing in place specifically to avoid SQL injection.

The problem comes when someone else copies your excellent working code,
but doesn't know about SQL injection. And then they create a web
front-end, so your customers can check your inventory or whatever.

Because *then*....you're screwed.

Rory

On Mon, Aug 1, 2011 at 12:54 PM, Monnier, Gary
<Gary.Monnier@xxxxxxxxx>wrote:

So tell me, how did userEnteredValue not get verified/edited?

Gary



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Charles Wilt
Sent: Monday, August 01, 2011 12:37 PM
To: RPG programming on the IBM i / System i
Subject: Re: Reduce large amount of logicals in SUBFL pgm,take in
another direction

Fine...

So tell me how this could be safe?
wSqlStmt = 'SELECT * FROM MYTABLE WHERE MYFLD = ' + userEnteredValue;

Charles

On Mon, Aug 1, 2011 at 3:27 PM, Monnier, Gary <Gary.Monnier@xxxxxxxxx>
wrote:
Charles,

With respect, I do understand the issue. I simply disagree with
your
assessment.

Gary



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Charles Wilt
Sent: Monday, August 01, 2011 11:48 AM
To: RPG programming on the IBM i / System i
Subject: Re: Reduce large amount of logicals in SUBFL pgm,take in
another direction

Gary,

I wouldn't call this a matter of disagreement ...

With respect, you obviously don't understand the issue....but it's
an
important issue. I'd be happy to clarify the problem, but I don't
know any better way to explain it. Perhaps Scott, Joe or Jon can jump

in with a better explanation.

Or perhaps you can explain why you think your code is safe because
it's
in a module...

You might start by posting the actual code, along with sample
usage...

Perhaps then somebody will be able to give you a concrete example of

how
it could be misued.

Sincerely,
Charles

On Mon, Aug 1, 2011 at 2:25 PM, Monnier, Gary
<Gary.Monnier@xxxxxxxxx>
wrote:
Charles,

So we choose to disagree.

Gary


-----Original Message-----
From: rpg400-l-bounces+gary.monnier=terex.com@xxxxxxxxxxxx
[mailto:rpg400-l-bounces+gary.monnier=terex.com@xxxxxxxxxxxx] On
Behalf Of Charles Wilt
Sent: Monday, August 01, 2011 11:19 AM
To: RPG programming on the IBM i / System i
Subject: Re: Reduce large amount of logicals in SUBFL pgm,take in
another direction

Gary,

You seem to be hung up on *MODULE...

I repeat, it doesn't matter where the statement is built. If
you're
building a statement dynamically with concatenation of user supplied
string.
The code is vulnerable. It doesn't have anything to do with *PGM,
*MODULE, *SRVPGM, authority or debug mode.

Charles

On Mon, Aug 1, 2011 at 1:54 PM, Monnier, Gary
<Gary.Monnier@xxxxxxxxx>
wrote:
Charles,

With respect you seem to be hung up on my example being a *PGM. I
recommended *MODULE. If you feel someone can get to a *PGM build from

*MODULEs and can inject an SQL statement then again I assert security
settings to the program are set incorrectly. Either you allow *PUBLIC

to debug the program or you have had a security breach involving a
profile with enough authority to debug the program. If the executable

*PGM allows modules and or service programs to be changed then you
also have a security hole. In both cases it is not my example causing

the breach and other much larger security issues are in play.

Respectfully,

Gary Monnier


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Charles Wilt
Sent: Monday, August 01, 2011 6:06 AM
To: RPG programming on the IBM i / System i
Subject: Re: Reduce large amount of logicals in SUBFL pgm,take in
another direction

Gary,

If you think that your program doesn't open you up to SQL
injection,
you are sadly mistaken...

The fact that the procedure is bound statically by reference or by

copy
as opposed to a dynamic called *PGM has no bearing.

SQL injection attacks can occur anytime you dynamically build a
statement and concatenate user string input into the statement. It
doesn't matter where the statement is built.

Again, all that matters is that in some way shape or form, you are
building a statement like so:
wSqlStmt = 'SELECT * FROM MYTABLE WHERE MYFLD = ' +
userEnteredValue;

Theoretically, you could parse and sanitize the user input,
making sure it's safe before using it. However, unlike some
languages RPG doesn't have that functionality built in. Also,
IMHO you're dependent on the guy who wrote the sanitizer being
smarter than the hackers :)

The safe way to do dynamic statements is via parameter markers.
You
build a statement like so:
wSqlStmt = 'SELECT * FROM MYTABLE WHERE MYFLD = ?';

then when you open/execute it, you pass in the variables to use at

the
parameter markers.
open C1 using :userEnteredValue;

With respect to PCI requirements...
6.5 Develop applications based on secure coding guidelines and
review
custom application code to identify coding vulnerabilities. Follow
up-to-date industry best practices to identify and manage
vulnerabilities.

OWASP is one of the standards usually used for secure
coding...their
top security risk for 2010...injection (SQL queries, LDAP queries,
XPath queries, OS commands, program arguments, etc. ).
https://www.owasp.org/index.php/Category:OWASP_Top_Ten_Project

Thus, dynamic SQL as used by your programs would fail an secure
code
review and you'd likely fail a PCI audit.

HTH,
Charles






On Fri, Jul 29, 2011 at 2:26 PM, Monnier, Gary
<Gary.Monnier@xxxxxxxxx>
wrote:
Your opinion Charles and what seems a very strong opinion. J



Yes, I've heard of SQL Injection attacks and no my suggestion
does not leave you open to this sort of attack. I've also heard
of LDAP injection attacks.



What I suggested does not impact PCI compliance or any other
security parameters. Nor does it impact FDA compliance. All the

MODULE does is build an SQL string. When bound with other
modules to make an executable object there are no compliance
issues.



If you create ILE programs that allow updating modules or service

programs then you have a behavior that needs changing. My
opinion is, and it is only my opinion, you should NEVER create a
program with Allow update. You are just asking for trouble in
the ILE world.



If you have ulcer causing issues with pgmToBuildSQL make it a
copy module rather than a bound module.



Regards,



Gary





-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Charles Wilt
Sent: Friday, July 29, 2011 10:35 AM
To: RPG programming on the IBM i / System i
Subject: Re: Reduce large amount of logicals in SUBFL pgm,take in

another direction



Very, very BAD IDEA!



Horrible in fact.



I hope you're not subject to PCI compliance rules, as the code
you posted pretty much guarantees an automatic failure.



Try googleing for "SQL injection"...



Charles



On Fri, Jul 29, 2011 at 1:16 PM, Monnier, Gary
<Gary.Monnier@xxxxxxxxx <mailto:Gary.Monnier@xxxxxxxxx> > wrote:

Sharon,



The process that builds your SQL statement can have parameters
passed

to it. One of these parameters can be a list of selections.

Something like this.



pgmToBuildSQL PR

nbrFieldsForWhereClause

arrayOfFieldsForWhereClause

arrayOfValuesForWhereClause





SQLStringBegin = 'Select * From yourfile ';



X = 1;

startPos = 1;



doW (X < = nbrFieldsForWhereClause);



whereValue = arrayOfFieldsForWhereClause(X) +

arrayOfValuesForWhereClause(X); //ValueFor can be = value, like

value, etc

valueLen = %len(%trimr(whereValue));

%subst(whereClause:startPos:valueLen) = whereValue;

startpos = startPos + valueLen + 1;

X = X + 1;



enddo;



Return;



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http://www.linkedin.com/in/roryhewitt
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