Critical Vulnerability in Perl Module Installer Let Attackers Intercept Traffic

A critical vulnerability has been identified in App::cpanminus (cpanm), a widely used tool for downloading and installing Perl modules.

This vulnerability, CVE-2024-45321, exposes users to potential cyber threats. It allows attackers to intercept and manipulate traffic during module installation.

CVE-2024-45321 – Vulnerability Details

App::cpanminus, known for its lightweight and efficient handling of Perl module installations, is configured by default to use HTTP rather than the more secure HTTPS protocol.

This oversight results in a CWE-494: Download of Code Without Integrity Check weakness, which network attackers can exploit to execute arbitrary code.

The lack of encryption in HTTP communications means that attackers could potentially intercept and alter the transmitted data, posing a severe risk to users relying on cpanminus for module installations.

Mitigations

Currently, there is no official patch available from the developers of cpanminus.

However, users can employ several mitigation strategies to safeguard their systems:

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Option 1: Set a HTTPS Mirror

Users can configure cpanminus to use a secure HTTPS mirror. This can be done by using the –from command-line argument:

$ cpanm --from https://www.cpan.org DISTNAME

Alternatively, users can set the PERL_CPANM_OPT environment variable to ensure all installations use HTTPS:

$ export PERL_CPANM_OPT="--from https://www.cpan.org"

It’s important to note that using this option will disable the ability to download older releases from BackPan and development (TRIAL) releases.

Option 2: Patch the cpanm Executable

Patching the cpanm executable is an option for users who need to retain support for BackPan and TRIAL releases.

This can be achieved with the following Perl one-liner:

$ perl -pi -E 's{http://(www\.cpan\.org|backpan\.perl\.org|cpan\.metacpan\.org|fastapi\.metacpan\.org|cpanmetadb\.plackperl\.org)}{https://$1}g' /path/to/cpanm

Option 3: Use an Alternative Client

Users may also consider switching to alternative clients that default to HTTPS, such as CPAN.pm (version 2.35 or later) or App::cpm, which offer secure module installations.

The Perl community and developers actively discuss the issue on platforms like GitHub.

Discussions focus on making cpanminus secure by default and exploring long-term solutions to prevent similar vulnerabilities.

 This vulnerability highlights the critical importance of secure communications in software installations. Users are urged to implement these mitigations promptly to protect their systems from potential threats.

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