Guarding against database anti-forensics

Network World - Database hacking has gone mainstream and is becoming harder to detect because of the increasingly sophisticated anti-forensic procedures hackers use to cover their tracks.

Knowing forensics inside and out, as well as the tricks hackers use to foil forensics, is essential for professionals responsible for protecting the integrity of corporate data.

Databases contain a high percentage of confidential data, yet many organizations lack the budget and management buy-in to implement protections. According to studies, 60% of organizations have experienced a breach in the past 12 months, 80% expect database attacks to increase and 40% on average fail security audits.

There are plenty of tools to help thwart attacks -- such as vulnerability management products that include vulnerability assessment and user monitoring functionality -- but the trick is to deploy comprehensive solutions that help in forensics and provide visibility into how attackers cover their tracks.

Common anti-forensics methodologies

Where database actions are traced by different logging mechanisms such as backup, trace, transaction and operating system logs, sophisticated attackers try to hide their activities by gaining database administrator privileges to manipulate those logs.

Some common ways attackers obtain administrator privileges include:

* Exploiting a vulnerability.

* Finding a valid login and password (by brute force, guessing, stealing or with the help of a trojan).

* Taking advantage of weak or missing access controls.

* Exploiting a vulnerability in an application or in the operating system.

Attackers interfere with logs using the following techniques:

* Disable logging. Some logging mechanisms can be disabled by administrators by just running a command in the database server. This is the easiest way to avoid some logging mechanisms.

* Intercept and modify logging mechanisms. On most database management systems (DBMS), it's possible to extend functionality by loading external libraries. These libraries have code that can be executed inside the database server process. As a result, the code will have unrestricted access to all database process memory and components, allowing an attacker to manipulate logs at will. The attacker will be able to modify database server memory to intercept and avoid logging, insert backdoors, hijack user sessions and so on.

* Impersonate other database users. Because some DBMS allow privileged users to execute commands under different user accounts, it's possible to impersonate any user. When logs are reviewed after an attack they will point to an innocent user and send forensic investigators after false leads.

* Abuse logging mechanism design. With some database servers it's possible to delete and/or overwrite logs. Some logging mechanisms are designed to reuse log space after certain conditions are met. Log space can also be reduced with specific commands, forcing the oldest log entries to be deleted and/or overwritten. Attackers can force these conditions or execute commands to delete and/or overwrite log entries.