Exploiting Vulnerability
What Is a Vulnerability?
To understand how these terms are used, it helps to understand exactly what’s at stake. It all starts with an API. API stands for application program interface, and the term refers to the guidelines that direct software on how to interact with the network and hardware. An API essentially gives commands for how the software should behave. APIs come in all shapes and sizes, and are generally straightforward to install.
A vulnerability, in turn, is really just an unintended API that has not been documented in the system. Once the API is found, attackers can use it to direct software to act in a way that it’s not intended to, such as gleaning information about the current security defenses in place. With vulnerabilities, hackers are typically attempting to solve a puzzle about what they can get away with before they attack.
A vulnerability scanner will automatically parse through the APIs to identify which ones may be exposing the system to danger. A vulnerability database is the list of known vulnerabilities the scanner will use to spot potential problems; the more information the scanner has, the more accurate its performance. Once a team has a report of the vulnerabilities, developers can use penetration testing as a means to see where the weaknesses are, so the problem can be fixed and future mistakes can be avoided. When employing frequent and consistent scanning, you'll start to see common threads between the vulnerabilities for a better understanding of the full system. Learn more about vulnerability management and scanning here.
What Is an Exploit?
An exploit is the next step in a hacker's playbook after finding a vulnerability. Exploits exercise the unintended API, whether documented or not. Exploits are used for a number of different reasons, from gaining financial information to tracking a user's whereabouts. Exploits can take place behind firewalls where they're harder to spot, and they’ve been known to cause irreparable damage when gone undetected.
For example, there is specific malware hackers can install that will wait until a computer is at its weakest point (e.g., a VPN connection from an unsecured network) before activating. Much like vulnerabilities, the exploit database is used as a reference point before sending a virtual alarm to the user about what's taking place behind closed doors. Exploits are easiest to deal with in their preliminary stages, but it may still take weeks to fully resolve both the action and the underlying vulnerability that allowed the action to occur in the first place.
What Is a Threat?
A threat refers to the hypothetical event wherein a hacker uses the vulnerability. The threat itself will normally have an exploit involved, as it's a common way hackers will make their move. A hacker may make multiple exploits at the same time after assessing what will bring the most reward. While nothing disastrous may have happened yet at this stage, it can give a security team or individual insight into whether or not an action plan needs to be made regarding specific security measures.
Risk then refers to how likely it is the threat will actually occur based on the security parameters of the network. There is no guaranteed safety when it comes to making a machine hacker-proof, but prioritizing vulnerabilities and their threat level is taking the game to the next level when it comes to security management.
While it may seem like you’re constantly hearing about a new attack or cyber threat in the world, these terms can help give further context to the stages and dangers that security professionals deal with on a daily basis. So, what can you do to lower your overall risk? Security Information and Event Management (SIEM) is a systematic process that can make it easier to control what's happening on your network. SIEM tools can help companies set up strong, proactive defenses that work to fend off threats, exploits, and vulnerabilities to keep their environment safe.
Exploiting Vulnerable Systems
Exploits are specially crafted to take advantage of specific security vulnerabilities that are discovered after the vulnerability assessment phase. Exploitation is a part of penetration testing where we need to actually go ahead and simulate the damage that can be done if the vulnerability remains unpatched. This serves as proof-of-concept and removes any doubts pertaining to the impact of the vulnerability. During real world penetration testing, this does not mean ‘dropping tables’ from databases or causing a denial of service. It means leaving a mark on system(s) or network(s) after exploitation in most harmless manner possible.
Please note that successful exploitation heavily depends on how well one understands the exact nature and location of the vulnerability. Many commonly known vulnerabilities have publicly available exploits – such as those on exploit-db – but while solving CTF challenges, you will need to take the time to understand the weakness rather than seek a plug-and-play exploit.
About Net-Force Exploits Challenges
These challenges require that you provide the correct passwords that are revealed to you after solving them. You can attempt them in any order but you must be logged in to try potential passwords. ‘Exploits’ CTF challenges range from web-based exploitations to backend SQL injections. However, in some cases these are just ‘simulated challenges’. For instance, the challenge ‘UNION makes FORCE’ does not actually involve a backend database server. Hence, you need to send the exact SQL injection query that the designer is looking for, rather than any other (correct) alternatives.
Spoiler Alert!!
Please be advised that the following content provides solutions to the intriguing Exploits challenges on Net-Force. I recommend against read further without having tried your absolute best at the challenges first.
Solutions to Exploits Challenges 1 to 5
Exploit Challenge 1, Level 401: “Nice include system ;)”
Since this is the first challenge in this category, it is not as convoluted. In fact, the title of the challenge contains a big hint – ‘include system’. The PHP local file inclusionvulnerability is a very popular weakness that allows us to access important system files on the server via the web interface. In all probability, the hint in the title is pointing to local file inclusion.
What is a Security Vulnerability?
A security vulnerability is a weakness an adversary could take advantage of to compromise the confidentiality, availability, or integrity of a resource.
In this context a weakness refers to implementation flaws or security implications due to design choices. For instance, being able to overrun a buffer’s boundaries while writing data to it introduces a buffer overflow vulnerability. Examples of notable vulnerabilities are Heartbleed, Shellshock/Bash and POODLE.
Public Vulnerability Repositories
Zero-day vulnerabilities are vulnerabilities that have not been publicly disclosed and are kept private. There are several public vulnerability repositories available that allow interested parties to have easy access to information regarding known vulnerabilities. The most prominent vulnerability repositories are CVE, NVD and OVAL. CVE has established a referencing system for registering vulnerabilities called the CVE identifier (CVE-ID). CVE-IDs usually include a brief description of the security vulnerability and sometimes advisories, mitigation measures and reports.
Vulnerability Management
Vulnerability management identifies, classifies, evaluates, and mitigates vulnerabilities. IT security professionals perform the vulnerability management process in an organised and timely manner by following the steps described below:
Preparation: Define the scope of the vulnerability management process.
Vulnerability Scanning: Vulnerability scanners are automated tools that scan a system for known security vulnerabilities providing a report with all the identified vulnerabilities sorted based on their severity. Known vulnerability scanners are Nexpose, Nessus and OpenVAS.
Identification, Classification and Evaluation of the Vulnerabilities: The vulnerability scanner provides a report of the identified vulnerabilities.
Remediating Actions: The asset owner determines which of the vulnerabilities will be mitigated.
Rescan: Once the remediating actions are completed, a rescan is performed to verify their effectiveness.
Penetration Testing
Penetration testing is the assessment of the security of a system against different types of attacks performed by an authorised security expert. The tester attempts to identify and exploit the system’s vulnerabilities. The difference between a penetration test and an actual attack is that the former is done by a tester who has permission to assess the security of the system and expose its security weaknesses. In addition the tester is given certain boundaries to operate and perform this task.
There exist some confusion in the mind of the public over penetration testing and vulnerability scanning. The two approaches actually complement each other, with vulnerability scanning being one of the first steps of a penetration test.
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