CVE-2020-27637 in R Programming Language
Summary
by MITRE • 01/12/2021
The R programming language’s default package manager CRAN is affected by a path traversal vulnerability that can lead to server compromise. This vulnerability affects packages installed via the R CMD install cli command or the install.packages() function from the interpreter. Update to version 4.0.3
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Analysis
by VulDB Data Team • 02/11/2021
The vulnerability identified as CVE-2020-27637 represents a critical path traversal flaw within the R programming language's package management system, specifically affecting the Comprehensive R Archive Network (CRAN) infrastructure. This security weakness exists in the default package installation mechanisms of R, creating a potential attack vector that could allow malicious actors to manipulate the package installation process and potentially compromise the underlying server environment. The vulnerability impacts both the command-line interface R CMD install and the interactive R interpreter's install.packages() function, making it particularly concerning given the widespread use of R in data science and statistical computing environments.
The technical implementation of this path traversal vulnerability stems from inadequate input validation during package extraction and installation processes. When R processes package installations, it fails to properly sanitize file paths within package archives, allowing attackers to manipulate directory traversal sequences that can cause files to be extracted outside of the intended target directories. This flaw aligns with CWE-22 Path Traversal and represents a classic example of how insufficient path validation can lead to arbitrary file write operations. The vulnerability essentially allows an attacker to specify paths that would normally be restricted, potentially enabling them to overwrite critical system files or inject malicious code into the package installation directory.
The operational impact of CVE-2020-27637 extends beyond simple package management compromise, as it could enable attackers to achieve persistent access to systems running vulnerable R environments. When packages are installed through the affected R functions, the malicious code could be executed with the privileges of the user running the R process, potentially leading to privilege escalation or full system compromise. This vulnerability particularly affects organizations that rely heavily on R for data analysis, scientific computing, or statistical modeling, where R environments are often deployed on servers with elevated privileges. The attack surface includes not only individual workstations but also shared computing environments, cloud deployments, and automated data processing pipelines that utilize R package installations.
Organizations should immediately update their R installations to version 4.0.3 or later to remediate this vulnerability, as this update includes proper path validation mechanisms that prevent directory traversal attacks. System administrators should also implement additional monitoring for unusual package installation activities and consider restricting package installation permissions to trusted users only. The mitigation strategy should include verifying that all R environments, including those used in containerized deployments or cloud platforms, have been updated to the patched version. Security teams should also review existing package repositories to ensure no malicious packages have been installed through this vulnerability, as the path traversal could potentially allow attackers to install backdoor code within legitimate-looking packages. This vulnerability demonstrates the importance of proper input validation in package management systems and aligns with ATT&CK technique T1195.002 for Supply Chain Compromise, highlighting how package repositories can serve as attack vectors when proper security controls are not implemented.