REALLY HACKING SQL SERVER 2000 Less Theory – More Action Jasper Smith

Agenda Slammer review and Tools SQL Password Sniffing Decoding WITH ENCRYPTION Privilege Escalation UDP 1434 Exploits Links to security resources Questions ?

What’s not covered SQL Injection SQL Password Cracking

First the Good News ! The demos are all on SP2 ( ) A lot of these are fixed in SP3 Slammer means a lot of sites are already on SP3 or latest security hotfix Slammer served as a wakeup call and focused everyone's minds on security (if they weren’t already !!)

SQL Slammer (Sapphire/W32.Slammer) Memory resident worm that propagates via UDP Port 1434 and exploits a vulnerability in the SQL Server Resolution Service First patch available July 2002 Difficulty of installing security hotfixes hampered deployment (tools now available) Too many exposed servers without Firewalls MSDE difficult to patch and identify – installed by many products

Spread of Slammer – First 30 mins

Slammer cont… Because it used UDP rather than TCP it was only limited by available bandwidth At Slammer’s peak, it was scanning 55 million hosts per second and doubled it’s numbers every 8.5 seconds [2] [2] 75,000 hosts affected in first 10 minutes [2] [2] Officially the fastest spreading worm ever

SQL Security Tools SQL Scan Scans single PC,IP range or domain Can optionally stop and disable vulnerable instances SQL Check Scans single PC Can optionally stop and disable vulnerable instances SQL Critical Update Scans single PC Installs Slammer hotfix even if instance not at SP2 SMSDeploy SMS install pack to deploy SQL Critical Update

SQL Password Sniffing Password is not sent in clear text, however the “encryption” is weak and easily broken Information on the algorithm is available from Threat Profiling SQL Server by David Litchfield The password is converted to a wide character format (UNICODE) and each byte XOR'd with a constant fixed value of 0xA5 [1] [1]

SQL Password Sniffing Simply need to format captured network trace into a varbinary string and run a small UDF to crack Easy to spot password,every other byte is 0xA5 Application roles suffer same problem Let’s have a look at the UDF then a demo

dbo.decoder

PASSWORD DEMO

SQL Password Sniffing If at all possible use NT Authentication If you must use SQL Authentication then consider using SSL Encryption Can be enabled for specific connections or server wide for all connections IPSEC is also available on Windows 2000 and higher but considerably more effort to set up than SSL

Decoding WITH ENCRYPTION dSQLSRVD Good explanation of issues with it at “Security” by obscurity Key generation relies on Database GUID, object_id and colid from syscomments ALTER statement allows us to use the same key to encrypt our own “known” text thus algorithm degenerates to simple XOR encryption

DEMO WITH ENCRYPTION

Privilege Escalation – Jobs Any login can make themselves sysadmin with 5 lines of TSQL By default all logins can submit jobs SQL agent issues SETUSER N'guest' WITH NORESET when a non sysadmin runs a job Three vulnerable extended stored procedures xp_execresultset xp_printstatements xp_displayparamstmt These procedures cause a reconnection to SQL

Privilege Escalation – sysxlogins Only possible if you are a sysadmin Use sp_configure to allow updates For any NT login (group or user) Change xstatus from to 18 [1] This will allow you to login using SQL authentication by using the NT login name and no password. NT login still works as normal

DEMO PRIVILIGE ESCALATION

Privilege Escalation Apply SP3 or latest security hotfix Secure extended stored procedures Remove guest user from msdb Audit sysxlogins Audit members of Sysadmin (difficult)

UDP 1434 Exploit – SQLKill.Net UDP 1434 Buffer Overflows made famous by Slammer but reported and fixed July 02 First example uses a harmless discovery tool and changes 1 character from 2 to 8 Heap overflow caused by the strtok() function expecting a colon (:) but not finding one and passing a NULL pointer to the atoi() function causing an AV [1] [1]

DEMO KILL SQL SERVER

UDP 1434 Exploit - netcat Second example is more complicated Use a stack overflow to call back to netcat listening on attacker pc on UDP 53 Network traffic looks like a malformed DNS query and DNS dynamic update Gain remote shell on target server Running in the SQL Server process space Let’s steal a database and for fun delete it and all backups and create an empty database with the same name

DEMO NETCAT

UDP 1434 Exploit - Protection SP3 or latest security hotfix Firewall rules to block all UDP 1434 traffic IPSEC policies blocking UDP 1434 How to Block Specific Network Protocols and Ports by Using IPSec

Security Links Slammer Security

References [1] Threat Profiling SQL Server by David Litchfield [2]