pg_escape_string

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johniskew2 at yahoo dot com
31-May-2006 12:43


For those who escape their single quotes with a backslash (ie \') instead of two single quotes in a row (ie '') there has recently been a SERIOUS sql injection vulnerability that can be employed taking advantage of your chosen escaping method.  More info here: http://www.postgresql.org/docs/techdocs.50

Even after the postgre update, you may still be limited to what you can do with your queries if you still insist on backslash escaping. It's a lesson to always use the PHP functions to do proper escaping instead of adhoc addslashes or magic quotes escaping.

meng
28-May-2006 07:21


Since php 5.1 the new function pg_query_params() was introduced. With this function you can use bind variables and don't have to escape strings. If you can use it, do so. If unsure why, check the changelog for Postgres 8.0.8.

otix
25-Apr-2006 06:43


Creating a double-tick is just fine. It works the same as the backslash-tick syntax. From the PostgreSQL docs:



The fact that string constants are bound by single quotes presents an obvious semantic problem, however, in that if the sequence itself contains a single quote, the literal bounds of the constant are made ambiguous. To escape (make literal) a single quote within the string, you may type two adjacent single quotes. The parser will interpret the two adjacent single quotes within the string constant as a single, literal single quote. PostgreSQL will also allow single quotes to be embedded by using a C-style backslash.

dominik dot mueller at access dot unizh dot ch
16-Jan-2006 01:40


in reply to "rich at dicksonlife dot com"



use serialize() / unserialize() instead!

rich at dicksonlife dot com
19-Jul-2005 08:38


Here's some code I knocked up to turn an array of values into a string representation of an array. Note that I also add the external single quotes to make it a full string literal.



  //$t is array to be escaped. $u will be string literal.

  $tv=array();

  foreach($t as $key=>$val){

    $tv[$key]="\"" . 

      str_replace("\"",'\\"', str_replace('\\','\\\\',$val)) . "\"

";

  }

  $u= implode(",",$tv) ;

  $u="'{" . pg_escape_string($u) . "}'";



There's probably a better way of doing this. That's why I'm posting this here :)

tsharek at o2 dot pl
02-Mar-2005 07:34


IMO the stripslashes in this case is not very usefull. Because pg_escape_string change ' into '' (double ' - not "). I use in add to database this:

pg_escape_string(stripslashes($_GET['var'])) and is in 100% safe (i hope).



If I use addslashes in this case that well be lost space in database (\''' - this is 3 bytes)



ps. sorry for my english:)

17-Jul-2003 02:30


Here with 'abc'efg'  the middle ' terminates the string, however 'abc\'def' is one big string with a ' character in the middle.



If the user can terminate the string he can then put in the bad sql.  When prompted for Barcode the user could put in  DROP TABLE foo; SELECT '1



$query = sprintf ("SELECT * FROM a.tblcards WHERE barcode='%s'", pg_escape_string($barcode)); 



So you have to "clean" your variable coming in to prevent that.

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pg_escape_string

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