A server administrator notes that a legacy application often stops running due to a memory error. When reviewing the debugging logs, they notice code being run
calling an internal process to exploit the machine. Which of the following attacks does this describe?

A.
Zero-day

B.
Buffer overflow

C.
Cross site scripting

D.
Malicious add-on

Explanation:
This question describes a buffer overflow attack.
A buffer overflow occurs when a program or process tries to store more data in a buffer (temporary data storage area) than it was intended to hold. Since buffers
are created to contain a finite amount of data, the extra information – which has to go somewhere – can overflow into adjacent buffers, corrupting or overwriting the
valid data held in them. Although it may occur accidentally through programming error, buffer overflow is an increasingly common type of security attack on data
integrity. In buffer overflow attacks, the extra data may contain codes designed to trigger specific actions, in effect sending new instructions to the attacked
computer that could, for example, damage the user’s files, change data, or disclose confidential information. Buffer overflow attacks are said to have arisen
because the C programming language supplied the framework, and poor programming practices supplied the vulnerability.
Incorrect Answers:
A: A zero day vulnerability refers to a hole in software that is unknown to the vendor. This security hole is then exploited by hackers before the vendor becomes
aware and hurries to fix it –this exploit is called a zero day attack. Uses of zero day attacks can include infiltrating malware, spyware or allowing unwanted access
to user information. The term “zero day” refers to the unknown nature of the hole to those outside of the hackers, specifically, the developers. Once the vulnerability
becomes known, a race begins for the developer, who must protect users. Zero-day attacks are generally not used to attack legacy applications. Memory errors are
indicative of a buffer overflow attack. Therefore, this answer is incorrect.
C: Cross-site scripting (XSS) is a type of computer security vulnerability typically found in Web applications. XSS enables attackers to inject client-side script into
Web pages viewed by other users.
Cross-site scripting uses known vulnerabilities in web-based applications, their servers, or plug- in systems on which they rely. Exploiting one of these, attackers
fold malicious content into the content being delivered from the compromised site. When the resulting combined content arrives at the client-side web browser, it

has all been delivered from the trusted source, and thus operates under the permissions granted to that system. By finding ways of injecting malicious scripts into
web pages, an attacker can gain elevated access-privileges to sensitive page content, session cookies, and a variety of other information maintained by the
browser on behalf of the user. XSS attacks are not used to attack legacy applications. Memory errors are indicative of a buffer overflow attack. Therefore, this
answer is incorrect.
D: The application is a legacy application. It is therefore unlikely to have an add-on. The question states that the application often stops running due to a memory
error. Memory errors are indicative of a buffer overflow attack. Therefore, this answer is incorrect.

http://searchsecurity.techtarget.com/definition/buffer-overflow http://en.wikipedia.org/wiki/Cross-site_scripting
http://www.pctools.com/security-news/zero-day-vulnerability/