Remote Code Execution (RCE) WAHS Practice Questions (Page 2)

Questions 6–10

1. 6foundation · easy

   Which of the following is a primary mitigation against command injection vulnerabilities?

   • AUsing HTTPS to encrypt traffic.
   • BUsing parameterized queries or prepared statements when interacting with databases.
   • CDisabling JavaScript in the user's browser.
   • DAvoiding the use of system calls and instead using safe APIs or libraries that do not invoke a shell.
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2. 7foundation · easy

   How can an injection flaw lead to remote code execution on a web server?

   • ABy allowing user input to be concatenated into a string that is later interpreted as executable code or a system command.
   • BBy tricking a user into clicking a link that downloads a malicious file to the server.
   • CBy overwhelming the server with requests until it crashes and runs arbitrary code.
   • DBy causing the server to return an error message that reveals the underlying operating system version.
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4. 8application · medium

   A web application has a network diagnostic page that accepts an IP address and displays the ping output. During a penetration test, you submit `127.0.0.1; whoami` and the response includes the web server's user account. Which remediation would most directly prevent this attack while preserving the page's functionality?

   • AAdd a Web Application Firewall rule that blocks requests containing a semicolon.
   • BEscape all shell metacharacters in the user-supplied IP address before passing it to the ping command.
   • CRun the web server process under a low-privileged account so the injected command has limited impact.
   • DReplace the shell command with a socket-based ICMP library and validate the input as an IP address.
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5. 9expert · hard

   A legacy PHP application has multiple injection points: a command injection in a ping tool, a code injection via eval() in a template engine, and an insecure file upload that stores files under the web root. The team must prioritize a single mitigation that reduces the most risk across all three vulnerabilities, given limited development resources. Which mitigation should be implemented first?

   • AMove the upload directory outside the web root and disable script execution in the upload directory.
   • BImplement a Web Application Firewall (WAF) rule set that blocks common attack patterns.
   • CReplace the ping tool with a library that does not invoke a shell and validate the IP address format.
   • DRefactor the application to use a secure template engine that does not use eval() and enforce strict input validation.
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6. 10application · medium

   A Python Flask application has an endpoint that evaluates a user-supplied arithmetic expression using `eval()`. A developer wants to keep the feature but prevent code execution. Which approach is the safest?

   • AUse `eval()` inside a restricted namespace with no builtins.
   • BSanitize the input by removing all letters and underscores before calling `eval()`.
   • CReplace `eval()` with a dedicated arithmetic parser that only accepts numbers and operators.
   • DRun the `eval()` in a separate thread with a timeout.
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