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Format string attack

Format string attack

(also format string vulnerability, FS attack)

Format string attack definition

A format string attack represents a class of cyberattacks that capitalize on weaknesses within the format string operations of software programs. Attackers skillfully alter the input directed to these operations, allowing them to access or modify data in random memory locations. As a result, this may cause unintended information leaks, service disruptions, or even the execution of unauthorized remote code.

See also: buffer overflow attack, end-to-end encryption, SQL injection

Format string attack examples

  • Information disclosure: An attacker crafts a malicious format string to read sensitive data from the application’s memory, such as private keys or user credentials.
  • Denial of service: By using a malicious format string, the attacker can cause a buffer overflow, which may crash the application or the entire system.
  • Remote code execution: A skilled attacker manipulates the format string to overwrite a function’s return address, causing the program to execute malicious code.

Preventing format string attacks

  • Use secure coding practices, such as input validation and proper use of format string functions.
  • Regularly update software and apply security patches to fix known vulnerabilities.
  • Implement runtime protection mechanisms like address space layout randomization (ASLR) to make exploitation more difficult.
  • Use NordVPN to protect your internet connection and reduce the risk of attacks that exploit format string vulnerabilities.

Further reading

Ultimate digital security