What is Buffer Overflow?

What is buffer overflow?

Buffers are areas of memory set aside to hold data or executable code. When a buffer overflow happens, it can overwrite adjacent memory areas, which may contain other data or executable code. This overwriting is not a deliberate action by the transaction or program, but an unintended consequence of the vulnerability, which could have been prevented by bounds checking.

While not every overflow carries malicious intent, the behavior of buffer overflows can be exploited. Attackers can use them to disrupt the operation of other programs, causing them to malfunction, expose secrets, or even run malicious code. In fact, buffer overflow vulnerabilities are the most common security vulnerabilities today.

Types of buffer overflow attacks

The two most common areas that are targeted by buffer overflow attacks are the stack and the heap. However, these types of exploitations are significantly different from each other. Whereas stack exploitation relies on architecture and compiler calling conventions, heap exploitation relies on the target system’s heap manager.

Let’s look at the most common types of buffer overflow attacks:

• Stack-based buffer overflows: This is the simplest and most common overflow attack scenario because stack memory is only used by a single thread of execution. By carefully crafting the input, an attacker can overwrite the return address with a pointer to malicious code, often placed within the overflowing buffer itself.
• Heap-based buffer overflows: Heap-based attacks are more difficult to execute because of the global and complex nature of heap memory, which is used by all parts of an application. In these types of exploits, the attacker crafts malicious code that intentionally exceeds the boundaries of the heap memory buffer, which can lead to crashes or users being denied service.
• Integer overflows:  Integer overflows and buffer overflows are distinct types of vulnerabilities, although they can sometimes be related. Integer overflow attacks happen when an arithmetic operation attempts to establish a numeric value that is outside the range of representable digits. This can lead to attackers executing malicious programs or accessing escalated privileges.

Consequences of buffer overflow attacks

The consequences of a buffer overflow exploit depend on the type of attack and the intent of the attacker. Some possible outcomes include:

• System crash: The malicious code that has overwritten adjacent memory can corrupt important data structures, modify program flow, or introduce invalid instructions. When the system attempts to execute the corrupted code or access the overwritten data, it may encounter illegal operations, invalid memory addresses, or trigger unhandled exceptions. These conditions can trigger more exceptions or errors that the system cannot handle properly, leading to a crash.
• Loss of data and services: If a system crash happens as a result of a buffer overflow attack, then it may cause a loss of data and services for the company as well as its users.
• Entry point for cyber attack: Once an attacker has overwritten code on adjacent buffer memory, there may be an opportunity for the attacker to execute malicious code or programs on the vulnerable system or in the context of the affected application.
• Reputational damage: If attackers exploit a company’s software via buffer overflow, then it could directly impact the company’s users and cause substantial harm to its reputation.
• Financial fallout: Buffer overflow attacks can cost organizations significant amounts of money, including the effort to repair or restore systems and, even worse, ransom payments should the attack fully compromise operations.

How to prevent buffer overflow attacks

The best way for application developers to prevent buffer overflow exploits is to use secure programming practices, which can greatly reduce the chance of exploitable overflows within software applications. One way to achieve that is to employ programming languages with built-in protection and consistently test code to see when errors need to be fixed. However, even with all these best practices in place, an application may still be vulnerable.

Therefore, using exploit protection software is a good idea when trying to protect against vulnerabilities in buffer overflow. Managed Detection and Response (MDR) Services offer businesses 24/7 advanced prevention, detection, and remediation by industry experts, so IT teams never miss a threat.