CVE-2017-7435 in libzypp
Summary
by MITRE
In libzypp before 20170803 it was possible to add unsigned YUM repositories without warning to the user that could lead to man in the middle or malicious servers to inject malicious RPM packages into a users system.
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Analysis
by VulDB Data Team • 02/16/2023
The vulnerability identified as CVE-2017-7435 affects the libzypp library, a core component of the zypp package management system used primarily in openSUSE and SUSE Linux distributions. This flaw represents a significant security weakness in the package management infrastructure that could potentially allow attackers to compromise system integrity through unauthorized repository modifications. The vulnerability existed in libzypp versions prior to the 20170803 release, indicating a window of exposure where systems were vulnerable to malicious package injection attacks.
The technical flaw stems from insufficient verification mechanisms within the repository handling process of libzypp. Specifically, the library failed to properly validate the authenticity of YUM repositories before adding them to the system configuration. This omission allowed users to inadvertently or intentionally incorporate unsigned repositories into their package management setup without receiving any security warnings or alerts. The vulnerability is categorized under CWE-200, which deals with Information Exposure, as it enables unauthorized access to system package management functions. The lack of proper signature verification creates an attack surface where malicious actors could host compromised repositories that appear legitimate to the system.
The operational impact of this vulnerability extends beyond simple package management issues, as it creates opportunities for man-in-the-middle attacks and supply chain compromises. When unsigned repositories are added to the system, attackers can inject malicious RPM packages that would be installed without user knowledge or consent. This scenario directly aligns with ATT&CK technique T1195 which covers Supply Chain Compromise, and T1059 which addresses Command and Scripting Interpreter. The vulnerability essentially undermines the trust model of the package management system, allowing attackers to bypass the intended security controls that protect against unauthorized software installation. Systems running affected versions of libzypp could be compromised through legitimate-looking package updates that actually contain malicious code.
The security implications of CVE-2017-7435 are particularly severe because package management systems serve as foundational components for system security and updates. When attackers can inject malicious packages through unsigned repository channels, they gain a persistent foothold on the system that can be used for various malicious activities including data exfiltration, privilege escalation, or establishing backdoors. The vulnerability demonstrates a critical flaw in the principle of least privilege and trust verification within package management systems. Organizations relying on affected versions of libzypp would be vulnerable to sophisticated attacks that exploit the trust relationship between the package manager and repository sources. The lack of user warnings during repository addition creates a false sense of security that attackers can exploit to gain unauthorized system access. Remediation requires updating to libzypp version 20170803 or later, which implements proper repository signature validation and user notification mechanisms. Additionally, system administrators should review existing repository configurations to ensure no unsigned repositories remain in use, and implement monitoring for unauthorized repository modifications to detect potential compromise attempts.