CAPEC 76

Summary

Attack Execution Flow

1. Fingerprinting of the operating system:

   In order to create a valid file injection, the attacker needs to know what the underlying OS is.

   Attack Step Techniques

   ID	Attack Step Technique Description	Environments
   1	Port mapping. Identify ports that the system is listening on, and attempt to identify inputs and protocol types on those ports.	env-Local env-CommProtocol env-Peer2Peer env-ClientServer
   2	TCP/IP Fingerprinting. The attacker uses various software to make connections or partial connections and observe idiosyncratic responses from the operating system. Using those responses, he attempts to guess the actual operating system.	env-Embedded env-CommProtocol env-Peer2Peer env-ClientServer env-Web
   3	Induce errors to find informative error messages	env-All

   Indicators

   ID	type	Indicator Description	Environments
   1	Positive	The target software accepts connections via the network.	env-Embedded env-CommProtocol env-Peer2Peer env-ClientServer env-Web

   Outcomes

   ID	type	Outcome Description
   1	Success	Operating environment (operating system, language, and/or middleware) is correctly identified.
   2	Inconclusive	Multiple candidate operating environments are suggested.

   Security Controls

   ID	type	Security Control Description
   1	Preventative	Provide misleading information on TCIP/IP fingerprints (some operating systems can be configured to send signatures that match other operating systems).
   2	Preventative	Provide misleading information at the server level (e.g., Apache, IIS, WebLogic, etc.) to announce a different server software.
   3	Detective	Some fingerprinting techniques can be detected by operating systems or by network IDS systems because they leave the network connection half-open, or they do not belong to a valid, open connection.

2. Survey the Application to Identify User-controllable Inputs:

   The attacker surveys the target application to identify all user-controllable inputs, possibly as a valid and authenticated user

   Attack Step Techniques

   ID	Attack Step Technique Description	Environments
   1	Spider web sites for all available links, entry points to the web site.	env-Web
   2	Manually explore application and inventory all application inputs	env-All

   Outcomes

   ID	type	Outcome Description
   1	Success	The attacker develops a list of likely interesting path (application or OS related)

   Security Controls

   ID	type	Security Control Description
   1	Detective	Monitor velocity of page fetching in web logs. Humans who view a page and select a link from it will click far slower and far less regularly than tools. Tools make requests very quickly and the requests are typically spaced apart regularly (e.g. 0.8 seconds between them).
   2	Detective	Create links on some pages that are visually hidden from web browsers. Using IFRAMES, images, or other HTML techniques, the links can be hidden from web browsing humans, but visible to spiders and programs. A request for the page, then, becomes a good predictor of an automated tool probing the application.
   3	Preventative	Actively monitor the application and either deny or redirect requests from origins that appear to be automated.
   4	Detective	Monitor velocity of feature activations (non-web software). Humans who activate features (click buttons, request actions, invoke APIs, etc.) will do so far slower and far less regularly than tools. Tools make requests very quickly and the requests are typically spaced apart regularly (e.g. 0.8 seconds between them).

1. Vary inputs, looking for malicious results:

   Depending on whether the application being exploited is a remote or local one the attacker crafts the appropriate malicious input containing the path of the targeted file or other file system control syntax to be passed to the application

   Attack Step Techniques

   ID	Attack Step Technique Description	Environments
   1	SecurityDatabase\Alert\Inject context-appropriate malicious file path using network packet injection tools (netcat, nemesis, etc.)	env-CommProtocol env-Web env-Peer2Peer env-ClientServer
   2	SecurityDatabase\Alert\Inject context-appropriate malicious file path using web test frameworks (proxies, TamperData, custom programs, etc.) or simple HTTP requests	env-Web
   3	SecurityDatabase\Alert\Inject context-appropriate malicious file system control syntax	env-CommProtocol env-Web env-Peer2Peer env-ClientServer

   Indicators

   ID	type	Indicator Description	Environments
   1	Positive	Inventorying in prior step is successful.	env-All

   Outcomes

   ID	type	Outcome Description
   1	Success	One or more injections that are appropriate to the platform provoke an unexpected response from the software, which can be varied by the attacker based on the input.

1. Manipulate files accessible by the application:

   The attacker may steal information or directly manipulate files (delete, copy, flush, etc.)

   Attack Step Techniques

   ID	Attack Step Technique Description	Environments
   1	The attacker injects context-appropriate malicious file path to access the content of the targeted file.	env-All
   2	The attacker injects context-appropriate malicious file system control syntax to access the content of the targeted file.	env-All
   3	The attacker injects context-appropriate malicious file path to cause the application to create, delete a targeted file.	env-All
   4	The attacker injects context-appropriate malicious file system control syntax to cause the application to create, delete a targeted file.	env-All
   5	The attacker injects context-appropriate malicious file path in order to manipulate the meta-data of the targeted file.	env-All
   6	The attacker injects context-appropriate malicious file system control syntax in order to manipulate the meta-data of the targeted file.	env-All

   Outcomes

   ID	type	Outcome Description
   1	Success	The software performs an action the attacker desires. This might be displaying information, storing information in a file, delete a file or some other malicious activity.

   Security Controls

   ID	type	Security Control Description
   1	Detective	Use a system that logs file modification and/or access.
   2	Preventative	Make the application run in a low-privileged mode to prevent such attack to access important files.

Likelihood: High

Description

Skill or Knowledge Level: Low

To identify file system entry point and execute against an overprivileged system interface

Design: Enforce principle of least privilege.

Design: Ensure all input is validated, and does not contain file system commands

Design: Run server interfaces with a non-root account and/or utilize chroot jails or other configuration techniques to constrain privileges even if attacker gains some limited access to commands.

Design: For interactive user applications, consider if direct file system interface is necessary, instead consider having the application proxy communication.

Implementation: Perform testing such as pentesting and vulnerability scanning to identify directories, programs, and interfaces that grant direct access to executables.