In computer security, heap feng shui (also known as heap grooming [1] ) is a technique used in exploits to facilitate arbitrary code execution. [2] The technique attempts to manipulate the layout of the heap by making heap allocations of carefully selected sizes. It is named after feng shui, an ancient Chinese system of aesthetics that involves the selection of precise alignments in space.
The term is general and can be used to describe a variety of techniques for bypassing heap protection strategies. The paper often credited with naming the technique, "Heap Feng Shui in JavaScript", [3] used it to refer to an exploit in which a dangling pointer was aligned with a portion of an attacker-controlled chunk. However, it has also found usage in capture the flag events to describe attacks that exploit characteristics of heap layout, such as the spacing between chunks. [4]
In information security and programming, a buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations.
JavaScript, often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, often incorporating third-party libraries. All major web browsers have a dedicated JavaScript engine to execute the code on users' devices.
A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describes what is required in a JVM implementation. Having a specification ensures interoperability of Java programs across different implementations so that program authors using the Java Development Kit (JDK) need not worry about idiosyncrasies of the underlying hardware platform.
Feng shui ( ), sometimes called Chinese geomancy, is an ancient Chinese traditional practice which claims to use energy forces to harmonize individuals with their surrounding environment. The term feng shui means, literally, "wind-water". From ancient times, landscapes and bodies of water were thought to direct the flow of the universal Qi – “cosmic current” or energy – through places and structures. Because Qi has the same patterns as wind and water, a specialist who understands them can affect these flows to improve wealth, happiness, long life, and family; on the other hand, the wrong flow of Qi brings bad results. More broadly, feng shui includes astronomical, astrological, architectural, cosmological, geographical, and topographical dimensions.
A heap overflow, heap overrun, or heap smashing is a type of buffer overflow that occurs in the heap data area. Heap overflows are exploitable in a different manner to that of stack-based overflows. Memory on the heap is dynamically allocated at runtime and typically contains program data. Exploitation is performed by corrupting this data in specific ways to cause the application to overwrite internal structures such as linked list pointers. The canonical heap overflow technique overwrites dynamic memory allocation linkage and uses the resulting pointer exchange to overwrite a program function pointer.
Cross-site scripting (XSS) is a type of security vulnerability that can be found in some web applications. XSS attacks enable attackers to inject client-side scripts into web pages viewed by other users. A cross-site scripting vulnerability may be used by attackers to bypass access controls such as the same-origin policy. Cross-site scripting carried out on websites accounted for roughly 84% of all security vulnerabilities documented by Symantec up until 2007. XSS effects vary in range from petty nuisance to significant security risk, depending on the sensitivity of the data handled by the vulnerable site and the nature of any security mitigation implemented by the site's owner network.
Exec Shield is a project started at Red Hat, Inc in late 2002 with the aim of reducing the risk of worm or other automated remote attacks on Linux systems. The first result of the project was a security patch for the Linux kernel that emulates an NX bit on x86 CPUs that lack a native NX implementation in hardware. While the Exec Shield project has had many other components, some people refer to this first patch as Exec Shield.
Address space layout randomization (ASLR) is a computer security technique involved in preventing exploitation of memory corruption vulnerabilities. In order to prevent an attacker from reliably jumping to, for example, a particular exploited function in memory, ASLR randomly arranges the address space positions of key data areas of a process, including the base of the executable and the positions of the stack, heap and libraries.
Alexander Peslyak, better known as Solar Designer, is a security specialist from Russia. He is best known for his publications on exploitation techniques, including the return-to-libc attack and the first generic heap-based buffer overflow exploitation technique, as well as computer security protection techniques such as privilege separation for daemon processes.
A security hacker is someone who explores methods for breaching defenses and exploiting weaknesses in a computer system or network. Hackers may be motivated by a multitude of reasons, such as profit, protest, information gathering, challenge, recreation, or evaluation of a system weaknesses to assist in formulating defenses against potential hackers. The subculture that has evolved around hackers is often referred to as the "computer underground".
In computer security, executable-space protection marks memory regions as non-executable, such that an attempt to execute machine code in these regions will cause an exception. It makes use of hardware features such as the NX bit, or in some cases software emulation of those features. However, technologies that emulate or supply an NX bit will usually impose a measurable overhead while using a hardware-supplied NX bit imposes no measurable overhead.
Feng shui is the ancient Chinese practice of placement and arrangement of space to achieve harmony with the environment.
Memory safety is the state of being protected from various software bugs and security vulnerabilities when dealing with memory access, such as buffer overflows and dangling pointers. For example, Java is said to be memory-safe because its runtime error detection checks array bounds and pointer dereferences. In contrast, C and C++ allow arbitrary pointer arithmetic with pointers implemented as direct memory addresses with no provision for bounds checking, and thus are potentially memory-unsafe.
In computer security, heap spraying is a technique used in exploits to facilitate arbitrary code execution. The part of the source code of an exploit that implements this technique is called a heap spray. In general, code that sprays the heap attempts to put a certain sequence of bytes at a predetermined location in the memory of a target process by having it allocate (large) blocks on the process's heap and fill the bytes in these blocks with the right values.
JSONP, or JSON-P, is a historical JavaScript technique for requesting data by loading a <script>
element, which is an element intended to load ordinary JavaScript. It was proposed by Bob Ippolito in 2005. JSONP enables sharing of data bypassing same-origin policy, which disallows running JavaScript code to read media DOM elements or XMLHttpRequest data fetched from outside the page's originating site. The originating site is indicated by a combination of URI scheme, host name, and port number.
Clickjacking is a malicious technique of tricking a user into clicking on something different from what the user perceives, thus potentially revealing confidential information or allowing others to take control of their computer while clicking on seemingly innocuous objects, including web pages.
Alexander Sotirov is a computer security researcher. He has been employed by Determina and VMware. In 2012, Sotirov co-founded New York based Trail of Bits with Dino Dai Zovi and Dan Guido, where he currently serves as Chief Scientist.
JIT spraying is a class of computer security exploit that circumvents the protection of address space layout randomization (ASLR) and data execution prevention (DEP) by exploiting the behavior of just-in-time compilation. It has been used to exploit the PDF format and Adobe Flash.
Cross-site request forgery, also known as one-click attack or session riding and abbreviated as CSRF or XSRF, is a type of malicious exploit of a website where unauthorized commands are submitted from a user that the web application trusts. There are many ways in which a malicious website can transmit such commands; specially-crafted image tags, hidden forms, and JavaScript XMLHttpRequests, for example, can all work without the user's interaction or even knowledge. Unlike cross-site scripting (XSS), which exploits the trust a user has for a particular site, CSRF exploits the trust that a site has in a user's browser. In a CSRF attack, an innocent end user is tricked by an attacker into submitting a web request that they did not intend. This may cause actions to be performed on the website that can include inadvertent client or server data leakage, change of session state, or manipulation of an end user's account.
Row hammer is a security exploit that takes advantage of an unintended and undesirable side effect in dynamic random-access memory (DRAM) in which memory cells interact electrically between themselves by leaking their charges, possibly changing the contents of nearby memory rows that were not addressed in the original memory access. This circumvention of the isolation between DRAM memory cells results from the high cell density in modern DRAM, and can be triggered by specially crafted memory access patterns that rapidly activate the same memory rows numerous times.