Heartbleed bug poses serious threat to unpatched servers

Dick O'Brien, Symantec

The Heartbleed bug is the latest in a series of SSL/TLS vulnerabilities uncovered this year. TLS and its older predecessor SSL are both secure protocols for Internet communication and work by encrypting traffic between two computers.

In February, Apple had to patch two critical vulnerabilities affecting SSL in its software. It first issued an update for its mobile operating system iOS, which patched a flaw that enabled an attacker with a privileged network position to capture or modify data in sessions protected by SSL/TLS. Days later, a second update was issued, this time for its desktop operating system OS X, after it was discovered that the same vulnerability also affected it.

In March, a certificate vulnerability was found in security library GnuTLS, which is used in a large number of Linux versions, including Red Hat desktop and server products, and Ubuntu and Debian distributions of the operating system.

GnuTLS is an open source software implementation of SSL/TLS. The bug meant that GnuTLS failed to correctly handle some errors that could occur when verifying a security certificate. This could allow an attacker to use a specially crafted certificate to trick GnuTLS into trusting a malicious website. The vulnerability was immediately patched by GnuTLS.

Heartbleed is by far the most serious vulnerability in SSL/TLS to be uncovered of late. The nature of the bug and the fact that affects one of the most widely used implementations of SSL/TLS means that it poses an immediate risk.

Advice for businesses:

  • Anyone using OpenSSL 1.0.1 through 1.0.1f should update to the latest fixed version of the software (1.0.1g), or recompile OpenSSL without the heartbeat extension
  • After moving to a fixed version of OpenSSL, if you believe your web server certificates may have been compromised or stolen as a result of exploitation, contact the certificate authority for a replacement
  • Finally, and as a best practice, businesses should also consider resetting end-user passwords that may have been visible in a compromised server memory

Advice for consumers:

  • You should be aware that your data could have been seen by a third party if you used a vulnerable service provider
  • Monitor any notices from the vendors you use. Once a vulnerable vendor has communicated customers that they should change their passwords, users should do so
  • Avoid potential phishing emails from attackers asking you to update your password - to avoid going to an impersonated website, stick with the official site domain
  • Stick to reputable websites and services. They are most likely to have immediately addressed the vulnerability
  • Monitor your bank and credit card statements to check for any unusual transactions

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