Command Injection in Nagios NRPE 3.2.1
Summary
CVE-2020-6581: Nagios NRPE 3.2.1 has Insufficient Filtering because, for example, nasty_metachars interprets \n as the character \ and the character n (not as the \n newline sequence). Affects nrpe across 2 version ranges.
< 4.0.0-r0
< 86a77fe3a9cbfae990adc578834fd537f4fa8557
Fixed in 4.0.0-r0. How to fix ↓
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Background
Nagios NRPE (Nagios Remote Plugin Executor) is a plugin that allows remote execution of Nagios plugins on other Linux/Unix machines. It is commonly used for monitoring and managing remote hosts. The NRPE package is available in Alpine Linux versions 3.13 to 3.18. However, version 3.2.1 of NRPE is vulnerable to command injection.
Vulnerability Detail
The vulnerability (CVE-2020-6581) in Nagios NRPE 3.2.1 is due to insufficient filtering. The 'nasty_metachars' function in NRPE interprets the '\n' character as '\n' instead of a newline sequence. This can be exploited by an attacker to inject arbitrary commands. The impact of this vulnerability can be severe, allowing unauthorized remote code execution and potential compromise of the affected system.
How To Fix
Minimum fixed version
4.0.0-r0
This is the first release that contains the fix.
sudo apk add --upgrade nrpeTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, it is advised to sanitize user input and ensure that any commands passed to NRPE are properly validated and filtered. Implementing input validation and sanitization routines can help mitigate the risk of command injection.
Conclusion
The command injection vulnerability in Nagios NRPE 3.2.1 can lead to unauthorized remote code execution and compromise of the affected system. It is crucial to upgrade to version 4.0.0-r0 or apply appropriate input validation and sanitization measures to mitigate the risk. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
Nagios NRPE (Nagios Remote Plugin Executor) is a plugin that allows remote execution of Nagios plugins on other Linux/Unix machines. It is commonly used for monitoring and managing remote hosts.
Command injection is a security vulnerability that allows an attacker to execute arbitrary commands on a target system. In the case of Nagios NRPE, this vulnerability can be exploited to execute unauthorized commands on the affected system.
The impact of this vulnerability can be severe. It allows an attacker to execute arbitrary commands on the affected system, potentially leading to unauthorized access, data exfiltration, or complete compromise of the system.
To fix this vulnerability, it is recommended to upgrade to version 4.0.0-r0 of NRPE. This version includes the necessary fixes to properly handle metacharacters and prevent command injection. Upgrade instructions can be found in the official documentation of NRPE.
As a temporary workaround, it is advised to sanitize user input and ensure that any commands passed to NRPE are properly validated and filtered. Implementing input validation and sanitization routines can help mitigate the risk of command injection.
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