SMTP Command Injection Vulnerability in Ruby Mail Gem
Summary
CVE-2015-9097: The mail gem before 2.5.5 for Ruby (aka A Really Ruby Mail Library) is vulnerable to SMTP command injection via CRLF sequences in a RCPT TO or MAIL FROM command, as demonstrated by CRLF sequences immediately before and a... Affects ruby-mail versions < 2.6.1+dfsg1-1. Fixed in 2.6.1+dfsg1-1. How to fix ↓
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Background
The Ruby Mail gem is a widely used library in Ruby applications for sending and receiving emails. It provides a simple interface for composing and sending emails via SMTP, making it an essential tool for developers. However, prior to version 2.5.5, the library was susceptible to a critical vulnerability that allowed attackers to exploit SMTP commands, potentially compromising the integrity of email communications.
Vulnerability Detail
The vulnerability, identified as CVE-2015-9097, arises from the improper handling of CRLF (Carriage Return Line Feed) sequences in the RCPT TO or MAIL FROM commands. This flaw allows an attacker to inject arbitrary SMTP commands, which can lead to unauthorized actions being performed on the mail server. The ramifications of this vulnerability include the potential for data leakage, email spoofing, and other malicious activities that could disrupt email services or compromise sensitive information.
How To Fix
Minimum fixed version
2.6.1+dfsg1-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade ruby-mailTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If upgrading is not immediately possible, a temporary workaround is to sanitize input to the MAIL FROM and RCPT TO commands to prevent CRLF injection. This can be done by implementing input validation to reject any input containing CRLF sequences.
Conclusion
The CVE-2015-9097 vulnerability in the Ruby Mail gem poses significant risks to email communications through SMTP command injection. It is crucial for developers to upgrade to the patched version to ensure the security of their applications. Utilizing tools like Vulert can help monitor and alert for such vulnerabilities in real-time.
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FAQ
CVE-2015-9097 is a vulnerability in the Ruby Mail gem that allows for SMTP command injection via CRLF sequences.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The impacts include unauthorized actions on the mail server, data leakage, and email spoofing, which can compromise sensitive information.
The CVSS score for CVE-2015-9097 is 6.1, indicating a medium severity level.
Yes, you can implement input validation to sanitize the MAIL FROM and RCPT TO commands to prevent CRLF injection as a temporary measure.
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