SB2019100211 - Multiple vulnerabilities in Ruby

Description

This security bulletin contains information about 4 secuirty vulnerabilities.

1) Code injection (CVE-ID: CVE-2019-16255)

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to improper input validation in lib/shell.rb in Ruby when processing Shell#[] and its alias Shell#test. A remote attacker can send a specially crafted request and execute arbitrary Ruby code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

2) HTTP Response Splitting (CVE-ID: CVE-2019-16254)

The vulnerability allows a remote attacker to perform HTTP response splitting attack.

The vulnerability exists due to insufficient validation of CRLF sequences within the WEBrick in Ruby. A remote attacker can send a specially crafted request to the application and perform a spoofing attack.

3) Input validation error (CVE-ID: CVE-2019-16201)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input within the WEBrick::HTTPAuth::DigestAuth in Ruby due to a regular expression issue. A remote attacker can send a specially crafted request to the application and perform a denial of service attack.

4) Input validation error (CVE-ID: CVE-2019-15845)

The vulnerability allows a remote attacker to bypass certain security restrictions.

The vulnerability exists in Ruby due to insufficient validation of user-supplied files within File.fnmatch and File.fnmatch? functions when processing NUL byte in the filename. A remote attacker can bypass implemented security restrictions and gain unauthorized access to the system.

Remediation

Install update from vendor's website.

References

• https://www.ruby-lang.org/en/news/2019/10/01/code-injection-shell-test-cve-2019-16255/
• https://www.ruby-lang.org/ja/news/2019/10/01/ruby-2-4-8-released/
• https://www.ruby-lang.org/ja/news/2019/10/01/ruby-2-5-7-released/
• https://www.ruby-lang.org/ja/news/2019/10/01/ruby-2-6-5-released/
• https://hackerone.com/reports/327512
• https://www.ruby-lang.org/en/news/2019/10/01/http-response-splitting-in-webrick-cve-2019-16254/
• https://hackerone.com/reports/331984
• https://hackerone.com/reports/661722
• https://www.ruby-lang.org/en/news/2019/10/01/webrick-regexp-digestauth-dos-cve-2019-16201/
• https://hackerone.com/reports/44961
• https://www.ruby-lang.org/en/news/2019/10/01/ruby-2-4-8-released/
• https://www.ruby-lang.org/en/news/2019/10/01/ruby-2-5-7-released/
• https://www.ruby-lang.org/en/news/2019/10/01/ruby-2-6-5-released/
• https://www.ruby-lang.org/en/news/2019/10/01/nul-injection-file-fnmatch-cve-2019-15845/