Testing: Information Gathering
The first phase in security assessment is focused on collecting as much information as possible about a target application. Information Gathering is a necessary step of a penetration test.
This task can be carried out in many different ways.
Using public tools (search engines), scanners, sending simple HTTP requests, or specially crafted requests, it is possible to force the application to leak information by sending back error messages or revealing the versions and technologies used by the application.
Often it is possible to gather information by receiving a response from the application that, as a consequence of bad default configuration of the application server or web server, could reveal vulnerabilities in the configuration or bad server management.
Application fingerprint is the first step of the Information Gathering process; knowing the version and type of a running web server allows testers to determine known vulnerabilities and the appropriate exploits to use during testing.
Application discovery is an activity oriented to the identification of the web applications hosted on a web server/application server.
This analysis is important because many times there is not a direct link connecting the main application backend. Discovery analysis can be useful to reveal details such as web-apps used for administrative purposes. In addition, it can reveal old versions of files or artifacts such as undeleted, obsolete scripts crafted during the test/development phase or as the result of maintenance.
This phase of the Information Gathering process consists of browsing and capturing resources related to the application being tested. Search engines, such as Google, can be used to discover issues related to the web application structure or error pages produced by the application that have been exposed to the public domain.
Web applications may divulge information during a penetration test which is not intended to be seen by an end user. Information such as error codes can inform the tester about technologies and products being used by the application.
Such error codes can be easy to exploit without using any particular skill due to bad error handling strategy.
Often analysis of the infrastructure and topology architecture can reveal a great deal about a web application. Information such as source code, HTTP methods permitted, administrative functionality, authentication methods and infrastructural configurations can be obtained.
Clearly, focusing only on the web application will not be an exhaustive test. It cannot be as comprehensive as the information possibly gathered by performing a broader infrastructure analysis.
SSL and TLS are two protocols that provide, with the support of cryptography, secure channels for the protection, confidentiality, and authentication of the information being transmitted.
Considering the criticality of these security implementations, it is important to verify the usage of a strong cipher algorithm and its proper implementation.
During the configuration of a database server, many DB administrators do not adequately consider the security of the DB listener component. The listener could reveal sensitive data as well as configuration settings or running database instances.
This information could provide some useful hints needed to compromise the reservedness, integrity and availability of the stored data. An accurate security analysis of the DB listener configuration can allow for the acquisition this information.
Web applications hide some information that is usually not considered during the development or configuration of the application itself.
This data can be discovered in the source code, in the log files or in the default error codes of the web servers. A correct approach to this topic is fundamental during a security assessment.
The file extensions present in a web server or a web-app make it possible to identify the technologies which compose the target application, e.g. jsp and asp extensions. File extensions can also expose additional systems connected to the application.
Redundant, readable and downloadable files on a web server, such as old, backup and renamed files, are a big source of information leakage. It is necessary to verify the presence of these files because they may contain parts of source code, installation paths as well as passwords for applications and/or databases.
OWASP Testing Guide v2
Here is the OWASP Testing Guide v2 Table of Contents