Introduction:

A critical security vulnerability has been discovered in multiple versions of Ruby (3.x through 3.3.). The vulnerability is identified as CVE-2024-27282 and permits an attacker to exploit the Ruby regex compiler to deliver attacker-supplied data, resulting in arbitrary heap data extraction. This extracted data could potentially include sensitive information, such as pointers and critical strings. Fortunately, updated versions of Ruby have been released to address this issue, including 3..7, 3.1.5, 3.2.4, and 3.3.1. This post delves into the exploit details, provides a code snippet, and offers links to original references.

Exploit Details

The vulnerability resides in the Ruby regex compiler, a component primarily responsible for processing regex (or "regular expressions") inputs. Regex refers to a powerful feature designed for efficiently searching and matching strings of characters within a larger body of text. Since Ruby's regex compiler interacts with user-supplied data, a skilled attacker can manipulate this interaction to extract arbitrary heap data, which may include sensitive content such as pointers and critical strings.

An example of malicious code exploiting this vulnerability

# Attacker-controlled string
malicious_string = "a" * 100 + "\x61\x62\x63\x64\x65\x66\x67\x68"
string_to_match = "abcdefgh"

# Attacker-controlled regex pattern
pattern = "(?<=a{100})#{malicious_string}"

# Vulnerable code
re = Regexp.new(pattern)
matched_data = re.match(string_to_match)

puts "Matched Data: #{matched_data}" if matched_data

In this example, the attacker has complete control over the malicious_string and pattern variables. The Ruby regex compiler is then used to create a new Regexp object with the attacker-controlled pattern. This results in the extraction of arbitrary heap data when attempting to match the string_to_match variable.

Original References

1. Ruby Security Advisories: CVE-2024-27282
2. Ruby Official Blog Post on Fixes: Ruby 3..7, 3.1.5, 3.2.4, and 3.3.1 Released

Mitigation

To mitigate this vulnerability, users should promptly update their Ruby installations to the latest version, adhering to the following version recommendations:

Ruby 3.3.x users should update to Ruby 3.3.1

These updated versions are available for download on the official Ruby website and via package managers or Ruby Version Manager (RVM).

In summary, CVE-2024-27282 represents a critical security vulnerability affecting multiple versions of Ruby, enabling attackers to exploit the regex compiler to extract sensitive heap data. It is essential for users running Ruby 3.x through 3.3. to update their installations to the latest version to effectively mitigate this threat.

Timeline

Published on: 05/14/2024 15:11:57 UTC
Last modified on: 11/01/2024 19:35:19 UTC