SQL Injection Attacks and Defense - 2009

References • Chapter 10 443
Table 10.19 Continued. Encoded SQL Metacharacters
Character
Encoded Variants
) %29
%2529
%u0029
%uff09
%ef%bc%89
[SPACE] %20
%2520
%u0020
%ff00
%c0%a0
Troubleshooting SQL Injection Attacks
Table 10.20 lists some of the common challenges and errors that are frequently encountered
when attempting to exploit an SQL injection flaw across various platforms.
Table 10.20 Troubleshooting SQL Injection Reference
Error/Challenge
Challenge
Performing a UNION SELECT
attack where the original
query is retrieving a column
of type image
Error Message
Image is incompatible
with int /
The image data type cannot
be selected as DISTINCT
because it is not comparable.
Challenge
Injecting into an ORDER BY
clause
Solution
Change your UNION SELECT statement to
read UNION ALL SELECT. This resolves the
problem with UNION SELECT attempting to
perform a compare operation against an
image data type.
For example:
UNION ALL SELECT null, null, null
Microsoft SQL Server
Microsoft SQL Server supports stacked
queries using the semicolon character (;) to
begin each new query. A variety of attacks,
such as time-delay-based data retrieval and
Continued