Web Application Injection Attacks GCIH Practice Questions (Page 12)

Questions 56–60

1. 56foundation · easy

   What is the most effective way to prevent XXE attacks?

   • ADisabling external entity processing in the XML parser.
   • BValidating XML input with a regex.
   • CUsing a blacklist of dangerous XML tags.
   • DEncoding XML input in base64 before parsing.
   Reveal Solution Discussion Select an answer first
2. 57foundation · easy

   What is a common impact of a buffer overflow vulnerability?

   • ASQL injection into the database.
   • BArbitrary code execution or denial of service.
   • CLDAP injection into the directory service.
   • DCross-site scripting in the browser.
   Reveal Solution Discussion Select an answer first
4. 58application · medium

   A legacy file-conversion utility on a Linux server accepts a filename from a web form and passes it to the shell command: system("convert " . $filename . " output.pdf"). An analyst discovers that submitting a filename like "; cat /etc/passwd; #" causes the contents of /etc/passwd to appear in the response. The application must continue to accept arbitrary filenames from authenticated users. Which remediation is the most secure and practical?

   • AValidate that the filename ends with .pdf before calling system()
   • BFilter out semicolons and hash characters from the filename
   • CRun the conversion as an unprivileged user with a restricted shell
   • DUse escapeshellarg() on the filename before passing it to system()
   Reveal Solution Discussion Select an answer first
5. 59application · medium

   A web application allows users to submit a 'name' field that is used in the 'From' header of an email. An attacker submits the following input: `victim@example.com\r\nBcc: attacker@example.com`. What is the likely impact?

   • AThe attacker can add a Bcc header, causing the email to be secretly sent to the attacker
   • BThe attacker can read the contents of the mail server's file system
   • CThe attacker can execute arbitrary code on the mail server
   • DThe attacker can cause a denial of service by crashing the mail server
   Reveal Solution Discussion Select an answer first
6. 60foundation · easy

   What is the primary mitigation for format string vulnerabilities?

   • ANever passing user input as the format string; always use a fixed format string.
   • BEscaping percent signs in user input.
   • CUsing a web application firewall to block format string payloads.
   • DDisabling printf in the application.
   Reveal Solution Discussion Select an answer first