What is a heartbleed bug? 

The Heartbleed bug is classified within the Common Vulnerabilities and Exposures of the Standard for Information Security Vulnerability Names maintained by MITRE as CVE-2014-0160. It’s a buffer over-read – a case when a system allows data access that should be restricted.  

Heartbleed vulnerabilities allow attackers to steal the private key of a server certificate. If the server version is vulnerable to Heartbleed, cybercriminals can retrieve the private key and impersonate the server. The consequences can be quite dire, as secure connections to the server are not possible anymore, and private information can be easily exposed. 

How does the heartbleed bug work? 

The mechanism behind the heartbleed vulnerability is, in fact, not very complex. However, it entails the exploitation of inappropriate input validation in the heartbeat extension.  

The SSL standard has an option to send a ‘heartbeat’ — a computer can send a message to the other end of the connection to check if the other computer is online by getting a ‘beat’ back. Attackers can use the heartbeat request functionality to send a malicious message instead of a regular one. This can make the computer on the receiving end accept and transmit secret data — including the server’s memory.  

By exploiting the heartbeat option and the lack of a proper bounds check, attackers can gain access to the secret keys that encrypt personal data such as names and passwords and the transferred content.  

The leakages can include primary and secondary key material, actual content, and collateral. Primary key materials are the encryption keys, which would allow decryption of traffic, while secondary key material means credentials like usernames and passwords. Content can include emails, instant messages, documents, Social Security Numbers, medical records, and financial details. As for collateral, it can span technical details like security mechanisms and memory addresses.   

In turn, this data can be used by malicious users for eavesdropping, user impersonation, and data theft. The worst part is that no traces are left during the attack — and it’s executed without any credentials. This makes it difficult to tackle the actual security instructions that may have occurred.  

The heartbleed security hole is not considered a design flaw in SSL/TLS protocol. Instead, it’s a programming error in the implementation that affects the OpenSSL cryptographic library, which provides SSL/TLS encryption to applications and services. 

What is a heartbleed attack? 

Heartbleed attacks allow attackers to steal a server certificate’s private key. Cybercriminals can get the private key and impersonate the server if the server version is vulnerable to Heartbleed. The results can be disastrous, as secure connections to the server are no longer feasible, and personal information is at risk of being revealed. 

How do heartbleed attacks start? 

In late 2011, the 31-year-old German engineer Robin Seggelmann contributed the defective Heartbeat functionality to an experimental version of OpenSSL, which lacked a validation method for a variable containing a length. Then its features were sent to OpenSSL for evaluation. However, the developer there missed the flaws as well. 

Before the problem was found and published, vulnerable versions of OpenSSL had been circulating for more than two years – since March 2012. As a result, computers running previous versions of OpenSSL (before 1.0.1) were unaffected. 

See how Veracode Dynamic Analysis can help you prevent fingerprinting attacks to strengthen your software against attacks with a free, 14-day trial.

Start Today

Why should I scan my applications for heartbleed vulnerabilities? 

The Heartbleed vulnerability should be taken seriously because it is simple to exploit.  This exposure has been known for a long, and detecting assaults has been difficult. The flaw affects SSL (Secure Sockets Layer) and TLS (Transport Layer Security) protocols used for secure communications and privacy for a wide range of online services, including web, email, and instant messaging. It deceives web servers into sending data stored in their memory, exposing various sensitive personal data and content. 

How do you prevent heartbleed attacks? 

First, you need to update OpenSSL to the latest version. The following versions fixed the Heartbleed vulnerability: 

  • OpenSSL 1.0.1g  

  • OpenSSL 1.0.0 (not affected)  

  • OpenSSL 0.9.8 (not affected)  

  • E.g., run:  

  • apt-get update; apt-get upgrade # Debian / Ubuntu yum update # RHeL / CentOS pacman -Syu # Arch Linux 

  • This step is key because if you’re running vulnerable versions of OpenSSL, the risk of attacks remains. 

How does a heartbleed scanner work? 

OpenSSL can be used to create an encrypted connection between two computers. To make sure that both computers are available during the communication, the SSL standard provides a protocol called heartbeat. The heartbeat makes sure that both ends can verify that the connection to the other side is still open. 

When sending a heartbeat, one of the two ends sends a secret message, including the message’s length. When the other side receives this message, it replies with the same secret message. 

For example, Computer 1 sends a heartbeat with the secret message “heartbleed” and the length of 10. The second computer receives this message and replies with "heartbleed”. 

The heartbleed vulnerability occurred because the length of the secret was not validated. This means if the sender of the connection sends the secret "heartbleed” and the length 100, the receiver would return with 100 characters from its local memory. Since sensitive data is stored in the local memory, an attacker could exploit this vulnerability and extract this sensitive data. 

Detecting intruders and assessing the real exploitation attempts and successes of the heartbleed issue are challenging since the assaults leave no traces in the logs. With Veracode Dynamic Analysis (DAST), you have a quick and easy way to avoid these problems by securing your web application because the solution helps you check every web server misconfiguration and avoid heartbleed vulnerabilities in any SSL/TLS certificate. 

  • Reduce your vulnerability to hacking and protect your users from the OWASP Top 10 vulnerabilities. 

  • Scan and evaluate the security of third-party components in your online application. 

  • Analyze APIs and microservices security with an automated security testing tool. 

  • Integrate our vulnerability scanner into your development process and workflow with ease. 

  • Download PDF, JSON/XML, and CSV reports and share them effortlessly with colleagues, executives, and clients.