Two categorizes of finding Command Injection Vulnerabilities.
Black Box Testing:
Tester is given little to no information about the system. Only information tester has access to is the URL of the application and the scope of the engagement.
White Box Testing:
Tester is given complete access to the system, including access to the source code of the application.
Black Box Testing
Conduct application mapping with a Burp Proxy operating in a passive mode, intercepting and logging all outgoing requests generated within the application.
Access the application's URL and navigate through all user-accessible pages.
Take note of all input vectors that may communicate with the backend in order to comprehend the operational mechanisms of the application.
Attempt to discern the underlying logic of the application.
Detect and document all occurrences where the web application seems to be interacting with the underlying OS.
Conduct a comprehensive analysis of the application to identify all instances involving client-side input, as potential injection vulnerabilities may arise in the presence of such input.
Fuzz the application with command injection payloads.
Following the application fuzzing process, two potential scenarios may arise. In the case of an event like Command Injection, it becomes imperative to conduct a detailed analysis of the application's response to ascertain its vulnerability status.
In-Band Command Injection, the command's response is displayed within the application, allowing for analysis to determine the application's vulnerability.
In Blind Command Injection, the application does not display the command response, and in order to demonstrate its susceptibility to command injection, one can initiate a time delay by utilizing commands such as "ping" or "sleep."
For Example: if you trigger a time delay in the application and you wrote "sleep for 10 seconds" and the application takes 10 seconds to respond back to you, that means it's vulnerable to command injection.
To get impact, Data exfiltration from the application can be achieved by directing the command's response to the web root, allowing for straightforward file retrieval via a standard web browser.
For Example: One could execute the Dir command and subsequently redirect its output to a directory accessible through the web root for any user utilizing the application. As a result, the file becomes generated and is readily accessible for download. This demonstrates the effectiveness of the command injection, enabling the potential exfiltration of data through this technique.
Establish an out-of-band communication channel back to a server under your control, leveraging Burp Collaborator.
White Box Testing
Perform an extensive mapping of input vectors within the application, adopting a black-box approach..
Then, perform a thorough examination of the source code to identify any potential missing input vectors.
Once all input vectors have been thoroughly mapped, it is essential to conduct a source code review with the objective of identifying any instances where these input vectors may be included as parameters within functions responsible for executing system commands.
Any function executing system commands should undergo testing for potential command injection vulnerabilities.
Upon discovering a vulnerability, it is imperative to conduct testing to ascertain its exploitability.
Proficient in conducting comprehensive source code reviews, adept at identifying vulnerabilities, and skilled in formulating and testing hypotheses to assess defensive mechanisms.
Mastering Command Injection Part 2
How To Find Command Injection?
Two categorizes of finding Command Injection Vulnerabilities.
Black Box Testing:
White Box Testing:
Black Box Testing
Conduct application mapping with a Burp Proxy operating in a passive mode, intercepting and logging all outgoing requests generated within the application.
Access the application's URL and navigate through all user-accessible pages.
Take note of all input vectors that may communicate with the backend in order to comprehend the operational mechanisms of the application.
Attempt to discern the underlying logic of the application.
Detect and document all occurrences where the web application seems to be interacting with the underlying OS.
Conduct a comprehensive analysis of the application to identify all instances involving client-side input, as potential injection vulnerabilities may arise in the presence of such input.
Fuzz the application with command injection payloads.
&,&&,|,||,;,\n,`,$().Following the application fuzzing process, two potential scenarios may arise. In the case of an event like Command Injection, it becomes imperative to conduct a detailed analysis of the application's response to ascertain its vulnerability status.
In-Band Command Injection, the command's response is displayed within the application, allowing for analysis to determine the application's vulnerability.
In Blind Command Injection, the application does not display the command response, and in order to demonstrate its susceptibility to command injection, one can initiate a time delay by utilizing commands such as "ping" or "sleep."
For Example: if you trigger a time delay in the application and you wrote "sleep for 10 seconds" and the application takes 10 seconds to respond back to you, that means it's vulnerable to command injection.
To get impact, Data exfiltration from the application can be achieved by directing the command's response to the web root, allowing for straightforward file retrieval via a standard web browser.
Establish an out-of-band communication channel back to a server under your control, leveraging Burp Collaborator.
White Box Testing
Perform an extensive mapping of input vectors within the application, adopting a black-box approach..
Once all input vectors have been thoroughly mapped, it is essential to conduct a source code review with the objective of identifying any instances where these input vectors may be included as parameters within functions responsible for executing system commands.
Upon discovering a vulnerability, it is imperative to conduct testing to ascertain its exploitability.