Abuse of Functionality
Abuse of Functionality is an attack technique that uses a web site's own features and functionality to attack itself or others. Abuse of Functionality can be described as the abuse of an application's intended functionality to perform an undesirable outcome. These attacks have varied results such as consuming resources, circumventing access controls, or leaking information. The potential and level of abuse will vary from web site to web site and application to application. Abuse of functionality attacks are often a combination of other attack types and/or utilize other attack vectors.Examples
Some examples of Abuse of Functionality are:
Abusing Send-Mail Functions
Abusing Password-Recovery Flows
Abusing functionality to make unrestricted proxy requests
Brute Force Attack
A brute force attack is a method to determine an unknown value by using an automated process to try a large number of possible values. The attack takes advantage of the fact that the entropy of the values is smaller than perceived. For example, while an 8 character alphanumeric password can have 2.8 trillion possible values, many people will select their passwords from a much smaller subset consisting of common words and terms.Types of brute force attacks
Brute Forcing Log-in Credentials
Brute Forcing Session Identifiers
Brute Forcing Directories and Files
Brute Forcing Credit Card Information
A Buffer Overflow is a flaw that occurs when more data is written to a block of memory, or buffer, than the buffer is allocated to hold. Exploiting a buffer overflow allows an attacker to modify portions of the target process’ address space. This ability can be used for a number of purposes, including the following:
Control the process execution
Crash the process
Modify internal variables
The attacker’s goal is almost always to control the target process’ execution. This is accomplished by identifying a function pointer in memory that can be modified, directly or indirectly, using the overflow. When such a pointer is used by the program to direct program execution through a jump or call instruction, the attacker-supplied instruction location will be used, thereby allowing the attacker to control the process.
In many cases, the function pointer is modified to reference a location where the attacker has placed assembled machine-specific instructions. These instructions are commonly referred to as shellcode, in reference to the fact that attackers often wish to spawn a command-line environment, or shell, in the context of the running process.
Buffer overflows are most often associated with software written in the C and C++ programming languages due to their widespread use and ability to perform direct memory manipulation with common programming constructs. It should be emphasized, however, that buffer overflows can exist in any programming environment where direct memory manipulation is allowed, whether through flaws in the compiler, runtime libraries, or features of the language itself.
Content Spoofing is an attack technique that allows an attacker to inject a malicious payload that is later misrepresented as legitimate content of a web application.
Text Only Content Spoofing
A common approach to dynamically build pages involves passing the body or portions thereof into the page via a query string value. This approach is common on error pages, or sites providing story or news entries. The content specified in this parameter is later reflected into the page to provide the content for the page.Example:
The "title" parameter in this example specifies the content that will appear in the HTML body for the news entries. If an attacker where to replace this content with something more sinister they might be able to falsify statements on the destination website.Example:
Upon visiting this link the user would believe the content being displayed as legitimate. In this example the falsified content is directly reflected back on the same page, however it is possible this payload may persist and be displayed on a future page visited by that user.
Credential/Session Prediction is a method of hijacking or impersonating a web site user. Deducing or guessing the unique value that identifies a particular session or user accomplishes the attack. Also known as Session Hijacking, the consequences could allow attackers the ability to issue web site requests with the compromised user's privileges.
Many web sites are designed to authenticate and track a user when communication is first established. To do this, users must prove their identity to the web site, typically by supplying a username/password (credentials) combination. Rather than passing these confidential credentials back and forth with each transaction, web sites will generate a unique "session ID" to identify the user session as authenticated. Subsequent communication between the user and the web site is tagged with the session ID as "proof" of the authenticated session. If an attacker is able predict or guess the session ID of another user, fraudulent activity is possible.
When an attacker gets a user's browser to execute his/her code, the code will run within the security context (or zone) of the hosting web site. With this level of privilege, the code has the ability to read, modify and transmit any sensitive data accessible by the browser. A Cross-site Scripted user could have his/her account hijacked (cookie theft), their browser redirected to another location, or possibly shown fraudulent content delivered by the web site they are visiting. Cross-site Scripting attacks essentially compromise the trust relationship between a user and the web site. Applications utilizing browser object instances which load content from the file system may execute code under the local machine zone allowing for system compromise.
Cross-Site Request Forgery
A cross-site request forgery is an attack that involves forcing a victim to send an HTTP request to a target destination without their knowledge or intent in order to perform an action as the victim. The underlying cause is application functionality using predictable URL/form actions in a repeatable way. The nature of the attack is that CSRF exploits the trust that a web site has for a user. By contrast, cross-site scripting (XSS)  exploits the trust that a user has for a web site. Like XSS, CSRF attacks are not necessarily cross-site, but they can be. Cross-site request forgery is also known as CSRF, XSRF, one-click attack, session riding, confused deputy, and sea surf.
CSRF attacks are effective in a number of situations, including:
The victim has an active session on the target site.
The victim is authenticated via HTTP auth on the target site.
The victim is on the same local network as the target site.
Denial of Service
Denial of Service (DoS) is an attack technique with the intent of preventing a web site from serving normal user activity. DoS attacks, which are easily normally applied to the network layer, are also possible at the application layer. These malicious attacks can succeed by starving a system of critical resources, vulnerability exploit, or abuse of functionality.
Many times DoS attacks will attempt to consume all of a web site's available system resources such as: CPU, memory, disk space etc. When any one of these critical resources reach full utilization, the web site will normally be inaccessible.
As today's web application environments include a web server, database server and an authentication server, DoS at the application layer may target each of these independent components. Unlike DoS at the network layer, where a large number of connection attempts are required, DoS at the application layer is a much simpler task to perform.
The most common methodology for attackers is to first footprint the target's web presence and enumerate as much information as possible. With this information, the attacker may develop an accurate attack scenario, which will effectively exploit a vulnerability in the software type/version being utilized by the target host.
Multi-tier fingerprinting is similar to its predecessor, TCP/IP Fingerprinting (with a scanner such as Nmap) except that it is focused on the Application Layer of the OSI model instead of the Transport Layer. The theory behind this fingerprinting is to create an accurate profile of the target's platform, web application software technology, backend database version, configurations and possibly even their network architecture/topology.
Format String Attack
Format String Attacks alter the flow of an application by using string formatting library features to access other memory space. Vulnerabilities occur when user-supplied data are used directly as formatting string input for certain C/C++ functions (e.g. fprintf, printf, sprintf, setproctitle, syslog, ...).
If an attacker passes a format string consisting of printf conversion characters (e.g. "%f", "%p", "%n", etc.) as a parameter value to the web application, they may:
- Execute arbitrary code on the server
- Read values off the stack
- Cause segmentation faults / software crashes
Format String attacks are related to other attacks in the Threat Classification: Buffer Overflows and Integer Overflows. All three are based in their ability to manipulate memory or its interpretation in a way that contributes to an attacker's goal.
HTTP Response Smuggling
HTTP response smuggling is a technique to "smuggle" 2 HTTP responses from a server to a client, through an intermediary HTTP device that expects (or allows) a single response from the server.
One use for this technique is to enhance the basic HTTP response splitting technique in order to evade anti- HTTP response splitting measures. In this case, the intermediary is the anti-HTTP response splitting mechanism between the web server and the proxy server (or web browser). This use case is described in . Another use case is to spoof responses received by the browser. In this case a malicious web site serves the browser a page that the browser will interpret as originating from a different (target) domain. HTTP response smuggling can be used to achieve this when the browser uses a proxy server to access both sites.
HTTP Response Splitting
In the HTTP Response Splitting attack, there are always 3 parties (at least) involved:
- Web server, which has a security hole enabling HTTP Response Splitting
- Target - an entity that interacts with the web server perhaps on behalf of the attacker. Typically this is a cache server forward/reverse proxy), or a browser (possibly with a browser cache).
- Attacker - initiates the attack
The essence of HTTP Response Splitting is the attacker's ability to send a single HTTP request that forces the web server to form an output stream, which is then interpreted by the target as two HTTP responses instead of one response, in the normal case. The first response may be partially controlled by the attacker, but this is less important. What is material is that the attacker completely controls the form of the second response from the HTTP status line to the last byte of the HTTP response body. Once this is possible, the attacker realizes the attack by sending two requests through the target. The first one invokes two responses from the web server, and the second request would typically be to some "innocent" resource on the web server. However, the second request would be matched, by the target, to the second HTTP response, which is fully controlled by the attacker. The attacker, therefore, tricks the target into believing that a particular resource on the web server (designated by the second request) is the server's HTTP response (server content), while it is in fact some data, which is forged by the attacker through the web server - this is the second response.
HTTP Request Smuggling
HTTP Request Smuggling is an attack technique that abuses the discrepancy in parsing of non RFC compliant HTTP requests between two HTTP devices (typically a front-end proxy or HTTP-enabled firewall and a back-end web server) to smuggle a request to the second device "through" the first device. This technique enables the attacker to send one set of requests to the second device while the first device sees a different set of requests. In turn, this facilitates several possible exploitations, such as partial cache poisoning, bypassing firewall protection and XSS.
An Integer Overflow is the condition that occurs when the result of an arithmetic operation, such as multiplication or addition, exceeds the maximum size of the integer type used to store it. When an integer overflow occurs, the interpreted value will appear to have “wrapped around” the maximum value and started again at the minimum value, similar to a clock that represents 13:00 by pointing at 1:00.
For example, an 8-bit signed integer on most common computer architectures has a maximum value of 127 and a minimum value of -128. If a programmer stores the value 127 in such a variable and adds 1 to it, the result should be 128. However, this value exceeds the maximum for this integer type, so the interpreted value will “wrap around” and become -128.
LDAP Injection is an attack technique used to exploit web sites that construct LDAP statements from user-supplied input.
Lightweight Directory Access Protocol (LDAP) is an open-standard protocol for both querying and manipulating X.500 directory services. The LDAP protocol runs over Internet transport protocols, such as TCP. Web applications may use user-supplied input to create custom LDAP statements for dynamic web page requests.
When a web application fails to properly sanitize user-supplied input, it is possible for an attacker to alter the construction of an LDAP statement. When an attacker is able to modify an LDAP statement, the process will run with the same permissions as the component that executed the command. (e.g. Database server, Web application server, Web server, etc.). This can cause serious security problems where the permissions grant the rights to query, modify or remove anything inside the LDAP tree. The same advanced exploitation techniques available in SQL Injection can also be similarly applied in LDAP Injection.
Mail Command Injection
Mail Command Injection is an attack technique used to exploit mail servers and webmail applications that construct IMAP/SMTP statements from user-supplied input that is not properly sanitized. Depending on the type of statement taken advantage by the attacker, we meet two types of injections: IMAP and SMTP Injection. An IMAP/SMTP Injection may make it possible to access a mail server which you previously had no access to before-hand. In some cases, these internal systems do not have the same level of infrastructure security hardening applied to them as most front-end web servers. Hence, attackers may find that the mail server yields better results in terms of exploitation. On the other hand, this technique allows to evade possible restrictions that could exist at application level (CAPTCHA, maximum number of requests, etc.).
OS Commanding is an attack technique used for unauthorized execution of operating system commands.
OS Commanding is the direct result of mixing trusted code and untrusted data. This attack is possible when an application accepts untrusted input to build operating system commands in an insecure manner involving improper data sanitization, and/or improper calling of external programs. In OS Commanding, executed commands by an attacker will run with the same privileges of the component that executed the command, (e.g. database server, web application server, web server, wrapper, application). Since the commands are executed under the privileges of the executing component an attacker can leverage this to gain access or damage parts that are otherwise unreachable (e.g. the operating system directories and files).
The Path Traversal attack technique allows an attacker access to files, directories, and commands that potentially reside outside the web document root directory. An attacker may manipulate a URL in such a way that the web site will execute or reveal the contents of arbitrary files anywhere on the web server. Any device that exposes an HTTP-based interface is potentially vulnerable to Path Traversal.
Most web sites restrict user access to a specific portion of the file-system, typically called the "web document root" or "CGI root" directory. These directories contain the files intended for user access and the executable necessary to drive web application functionality. To access files or execute commands anywhere on the file-system, Path Traversal attacks will utilize the ability of special-characters sequences.
The most basic Path Traversal attack uses the "../" special-character sequence to alter the resource location requested in the URL. Although most popular web servers will prevent this technique from escaping the web document root, alternate encodings of the "../" sequence may help bypass the security filters. These method variations include valid and invalid Unicode-encoding ("..%u2216" or "..%c0%af") of the forward slash character, backslash characters ("..\") on Windows-based servers, URL encoded characters "%2e%2e%2f"), and double URL encoding ("..%255c") of the backslash character.
Even if the web server properly restricts Path Traversal attempts in the URL path, a web application itself may still be vulnerable due to improper handling of user-supplied input. This is a common problem of web applications that use template mechanisms or load static text from files. In variations of the attack, the original URL parameter value is substituted with the file name of one of the web application's dynamic scripts. Consequently, the results can reveal source code because the file is interpreted as text instead of an executable script. These techniques often employ additional special characters such as the dot (".") to reveal the listing of the current working directory, or "" NULL characters in order to bypass rudimentary file extension checks.
Predictable Resource Location
Predictable Resource Location is an attack technique used to uncover hidden web site content and functionality. By making educated guesses via brute forcing an attacker can guess file and directory names not intended for public viewing. Brute forcing filenames is easy because files/paths often have common naming convention and reside in standard locations. These can include temporary files, backup files, logs, administrative site sections, configuration files, demo applications, and sample files. These files may disclose sensitive information about the website, web application internals, database information, passwords, machine names, file paths to other sensitive areas, etc...
This will not only assist with identifying site surface which may lead to additional site vulnerabilities, but also may disclose valuable information to an attacker about the environment or its users. Predictable Resource Location is also known as Forced Browsing, Forceful Browsing, File Enumeration, and Directory Enumeration.
Remote File Inclusion
Remote File Include (RFI) is an attack technique used to exploit "dynamic file include" mechanisms in web applications. When web applications take user input (URL, parameter value, etc.) and pass them into file include commands, the web application might be tricked into including remote files with malicious code.
Almost all web application frameworks support file inclusion. File inclusion is mainly used for packaging common code into separate files that are later referenced by main application modules. When a web application references an include file, the code in this file may be executed implicitly or explicitly by calling specific procedures. If the choice of module to load is based on elements from the HTTP request, the web application might be vulnerable to RFI.
An attacker can use RFI for:
Running malicious code on the server: any code in the included malicious files will be run by the server. If the file include is not executed using some wrapper, code in include files is executed in the context of the server user. This could lead to a complete system compromise.
PHP is particularly vulnerable to RFI attacks due to the extensive use of "file includes" in PHP programming and due to default server configurations that increase susceptibility to an RFI attack
The WS-Routing Protocol (WS-Routing) is a protocol for exchanging SOAP messages from an initial message sender to an ultimate receiver, typically via a set of intermediaries. The WS-Routing protocol is implemented as a SOAP extension, and is embedded in the SOAP Header. WS-Routing is often used to provide a way to direct XML traffic through complex environments and transactions by allowing interim way stations in the XML path to assign routing instructions to an XML document.
Routing Detours are a type of "Man in the Middle" attack where Intermediaries can be injected or "hijacked" to route sensitive messages to an outside location. Routing information (either in the HTTP header or in WS-Routing header) can be modified en route and traces of the routing can be removed from the header and message such that the receiving application none the wiser that a routing detour has occurred. The header and the insertion of header objects is often less protected than the message; this is due to the fact that the header is used as a catch all for metadata about the transaction such as authentication, routing, formatting, schema, canonicalization, namespaces, etc. Also, many processes may be involved in adding to/processing the header of an XML document. In many implementations the routing info can come from an external web service (using WS-Referral for example) that provides the specific routing for the transaction.
WS-Addressing is a newer standard published by the W3C to provide routing functionality to SOAP messages. One of the key differences between WS-Routing and WS-Addressing is that WS-Addressing only provides the next location in the route. While little research has been done into the susceptibility of WS-Addressing to Routing Detour Attack, at least one paper (see reference #6 below) suggests that WS-Addressing is vulnerable to Routing Detour as well.
Session Fixation is an attack technique that forces a user's session ID to an explicit value. Depending on the functionality of the target web site, a number of techniques can be utilized to "fix" the session ID value. These techniques range from Cross-site Scripting exploits to peppering the web site with previously made HTTP requests. After a user's session ID has been fixed, the attacker will wait for that user to login. Once the user does so, the attacker uses the predefined session ID value to assume the same online identity.
Generally speaking there are two types of session management systems when it comes to ID values. The first type is "permissive" systems that allow web browsers to specify any ID. The second type is "strict" systems that only accept server-side-generated values. With permissive systems, arbitrary session IDs are maintained without contact with the web site. Strict systems require the attacker to maintain the "trap-session", with periodic web site contact, preventing inactivity timeouts.
Without active protection against Session Fixation, the attack can be mounted against any web site that uses sessions to identify authenticated users. Web sites using sessions IDs are normally cookie-based, but URLs and hidden form fields are used as well. Unfortunately, cookie-based sessions are the easiest to attack. Most of the currently identified attack methods are aimed toward the fixation of cookies.
In contrast to stealing a users' session IDs after they have logged into a web site, Session Fixation provides a much wider window of opportunity. The active part of the attack takes place before a user logs in.
SOAP Array Abuse
XML SOAP arrays are a common target for malicious abuse. SOAP arrays are defined as having a type of "SOAP-ENC:Array" or a type derived there from. SOAP arrays have one or more dimensions (rank) whose members are distinguished by ordinal position. An array value is represented as a series of elements reflecting the array, with members appearing in ascending ordinal sequence. For multi-dimensional arrays the dimension on the right side varies most rapidly. Each member element is named as an independent element. A web-service that expects an array can be the target of a XML DoS attack by forcing the SOAP server to build a huge array in the machine's memory, thus inflicting a DoS condition on the machine due to the memory pre-allocation.
SSI Injection (Server-side Include) is a server-side exploit technique that allows an attacker to send code into a web application, which will later be executed locally by the web server. SSI Injection exploits a web application's failure to sanitize user-supplied data before they are inserted into a server-side interpreted HTML file.
Before serving an HTML web page, a web server may parse and execute Server-side Include statements before providing it to the client. In some cases (e.g. message boards, guest books, or content management systems), a web application will insert user-supplied data into the source of a web page.
If an attacker submits a Server-side Include statement, he may have the ability to execute arbitrary operating system commands, or include a restricted file's contents the next time the page is served. This is performed at the permission level of the web server user.
SQL Injection is an attack technique used to exploit applications that construct SQL statements from user-supplied input. When successful, the attacker is able to change the logic of SQL statements executed against the database.
Structured Query Language (SQL) is a specialized programming language for sending queries to databases. The SQL programming language is both an ANSI and an ISO standard, though many database products supporting SQL do so with proprietary extensions to the standard language. Applications often use user-supplied data to create SQL statements. If an application fails to properly construct SQL statements it is possible for an attacker to alter the statement structure and execute unplanned and potentially hostile commands. When such commands are executed, they do so under the context of the user specified by the application executing the statement. This capability allows attackers to gain control of all database resources accessible by that user, up to and including the ability to execute commands on the hosting system.
URL Redirector Abuse
URL redirectors represent common functionality employed by web sites to forward an incoming request to an alternate resource. This can be done for a variety of reasons and is often done to allow resources to be moved within the directory structure and to avoid breaking functionality for users that request the resource at its previous location. URL redirectors may also be used to implement load balancing, leveraging abbreviated URLs or recording outgoing links. It is this last implementation which is often used in phishing attacks as described in the example below. URL redirectors do not necessarily represent a direct security vulnerability but can be abused by attackers trying to social engineer victims into believing that they are navigating to a site other than the true destination.
XPath Injection is an attack technique used to exploit applications that construct XPath (XML Path Language) queries from user-supplied input to query or navigate XML documents. It can be used directly by an application to query an XML document, as part of a larger operation such as applying an XSLT transformation to an XML document, or applying an XQuery to an XML document. The syntax of XPath bears some resemblance to an SQL query, and indeed, it is possible to form SQL-like queries on an XML document using XPath. For example, assume an XML document that contains elements by the name user, each of which contains three subelements - name, password and account.
XML Injection is an attack technique used to manipulate or compromise the logic of an XML application or service. The injection of unintended XML content and/or structures into an XML message can alter the intend logic of the application. Further, XML injection can cause the insertion of malicious content into the resulting message/document.
Application Misconfiguration attacks exploit configuration weaknesses found in web applications. Many applications come with unnecessary and unsafe features, such as debug and QA features, enabled by default. These features may provide a means for a hacker to bypass authentication methods and gain access to sensitive information, perhaps with elevated privileges.
Likewise, default installations may include well-known usernames and passwords, hard-coded backdoor accounts, special access mechanisms, and incorrect permissions set for files accessible through web servers. Default samples may be accessible in production environments. Application-based configuration files that are not properly locked down may reveal clear text connection strings to the database, and default settings in configuration files may not have been set with security in mind. All of these misconfigurations may lead to unauthorized access to sensitive information.
Automatic directory listing/indexing is a web server function that lists all of the files within a requested directory if the normal base file (index.html/home.html/default.htm/default.asp/default.aspx/index.php) is not present. When a user requests the main page of a web site, they normally type in a URL such as: http://www.example.com/directory1/ - using the domain name and excluding a specific file. The web server processes this request and searches the document root directory for the default file name and sends this page to the client. If this page is not present, the web server will dynamically issue a directory listing and send the output to the client. Essentially, this is equivalent to issuing an "ls" (Unix) or "dir" (Windows) command within this directory and showing the results in HTML form. From an attack and countermeasure perspective, it is important to realize that unintended directory listings may be possible due to software vulnerabilities (discussed in the example section below) combined with a specific web request.
Improper Filesystem Permissions
Improper filesystem permissions are a threat to the confidentiality, integrity and availability of a web application. The problem arises when incorrect filesystem permissions are set on files, folders, and symbolic links. When improper permissions are set, an attacker may be able to access restricted files or directories and modify or delete their contents. For example, if an anonymous user account has write permission to a file, then an attacker may be able to modify the contents of the file influencing the web application in undesirable ways. An attacker may also exploit improper symlinks to escalate their privileges and/or access unauthorized files; for example, a symlink that points to a directory outside of the web root.
Improper Input Handling
Improper input handling is one of the most common weaknesses identified across applications today. Poorly handled input is a leading cause behind critical vulnerabilities that exist in systems and applications.
Generally, the term input handing is used to describe functions like validation, sanitization, filtering, encoding and/or decoding of input data. Applications receive input from various sources including human users, software agents (browsers), and network/peripheral devices to name a few. In the case of web applications, input can be transferred in various formats (name value pairs, JSON, SOAP, etc...) and obtained via URL query strings, POST data, HTTP headers, Cookies, etc... Non-web application input can be obtained via application variables, environment variables, the registry, configuration files, etc... Regardless of the data format or source/location of the input, all input should be considered untrusted and potentially malicious. Applications which process untrusted input may become vulnerable to attacks such as Buffer Overflows, SQL Injection, OS Commanding, Denial of Service just to name a few.
Improper Output Handling
Output handling refers to how an application generates outgoing data. If an application has improper output handling, the output data may be consumed leading to vulnerabilities and actions never intended by the application developer. In many cases, this unintended interpretation is classified as one or more forms of critical application vulnerabilities.
Information Leakage is an application weakness where an application reveals sensitive data, such as technical details of the web application, environment, or user-specific data. Sensitive data may be used by an attacker to exploit the target web application, its hosting network, or its users. Therefore, leakage of sensitive data should be limited or prevented whenever possible. Information Leakage, in its most common form, is the result of one or more of the following conditions: A failure to scrub out HTML/Script comments containing sensitive information, improper application or server configurations, or differences in page responses for valid versus invalid data.
Failure to scrub HTML/Script comments prior to a push to the production environment can result in the leak of sensitive, contextual, information such as server directory structure, SQL query structure, and internal network information. Often a developer will leave comments within the HTML and/or script code to help facilitate the debugging or integration process during the pre-production phase. Although there is no harm in allowing developers to include inline comments within the content they develop, these comments should all be removed prior to the content's public release.
Insecure Indexing is a threat to the data confidentiality of the web-site. Indexing web-site contents via a process that has access to files which are not supposed to be publicly accessible has the potential of leaking information about the existence of such files, and about their content. In the process of indexing, such information is collected and stored by the indexing process, which can later be retrieved (albeit not trivially) by a determined attacker, typically through a series of queries to the search engine. The attacker does not thwart the security model of the search engine. As such, this attack is subtle and very hard to detect and to foil - it’s not easy to distinguish the attacker’s queries from a legitimate user’s queries.
Insufficient Anti-automation occurs when a web application permits an attacker to automate a process that was originally designed to be performed only in a manual fashion, i.e. by a human web user.
Web application functionality that is often a target for automation attacks may include:
Application login forms – attackers may automate brute force login requests in an attempt to guess user credentials
Service registration forms – attackers may automatically create thousands of new accounts
Email forms – attackers may exploit email forms as spam relays or for flooding a certain user’s mailbox
Account maintenance – attackers may perform mass DoS against an application, by flooding it with numerous requests to disable or delete user accounts
Account information forms – attackers may perform mass attempts to harvest user personal information from a web application
Comment forms / Content Submission forms – these may be used for spamming blogs, web forums and web bulletin boards by automatically submitting contents such as spam or even web-based malware
Forms tied to SQL database queries - these may be exploited in order to perform a denial of service attack against the application. The attack is performed by sending numerous heavy SQL queries in a short period of time, hence denying real users from service.
eShopping / eCommerce - eShopping and eCommerce applications that do not enforce human-only buyers, can be exploited in order to buy preferred items in large amounts, such as sporting events tickets. These are later sold by scalpers for higher prices.
Online polls - polls and other types of online voting systems can be automatically subverted in favor of a certain choice.
Web-based SMS message sending - attackers may exploit SMS message sending systems in order to spam mobile phone users
Insufficient Authorization results when an application does not perform adequate authorization checks to ensure that the user is performing a function or accessing data in a manner consistent with the security policy. Authorization procedures should enforce what a user, service or application is permitted to do. When a user is authenticated to a web site, it does not necessarily mean that the user should have full access to all content and functionality.
Insufficient Process Validation
Insufficient Process Validation occurs when a web application fails to prevent an attacker from circumventing the intended flow or business logic of the application. When seen in the real world, insufficient process validation has resulted in ineffective access controls and monetary loss.
There are two main types of processes that require validation: flow control and business logic.
Insufficient Session Expiration
Insufficient Session Expiration occurs when a Web application permits an attacker to reuse old session credentials or session IDs for authorization. Insufficient Session Expiration increases a Web site's exposure to attacks that steal or reuse user's session identifiers.
Insufficient Transport Layer Protection
Insufficient transport layer protection allows communication to be exposed to untrusted third-parties, providing an attack vector to compromise a web application and/or steal sensitive information. Websites typically use Secure Sockets Layer / Transport Layer Security (SSL/TLS) to provide encryption at the transport layer . However, unless the website is configured to use SSL/TLS and configured to use SSL/TLS properly, the website may be vulnerable to traffic interception and modification.
Server Misconfiguration attacks exploit configuration weaknesses found in web servers and application servers. Many servers come with unnecessary default and sample files, including applications, configuration files, scripts, and web pages. They may also have unnecessary services enabled, such as content management and remote administration functionality. Debugging functions may be enabled or administrative functions may be accessible to anonymous users. These features may provide a means for a hacker to bypass authentication methods and gain access to sensitive information, perhaps with elevated privileges.
Servers may include well-known default accounts and passwords. Failure to fully lock down or harden the server may leave improperly set file and directory permissions. Misconfigured SSL certificates and encryption settings, the use of default certificates, and improper authentication implementation with external systems may compromise the confidentiality of information.