CVE-2017-2623 in rpm-ostree
Summary
by MITRE
It was discovered that rpm-ostree and rpm-ostree-client before 2017.3 fail to properly check GPG signatures on packages when doing layering. Packages with unsigned or badly signed content could fail to be rejected as expected. This issue is partially mitigated on RHEL Atomic Host, where certificate pinning is used by default.
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Analysis
by VulDB Data Team • 09/02/2024
The vulnerability identified as CVE-2017-2623 affects rpm-ostree and rpm-ostree-client versions prior to 2017.3, specifically targeting the cryptographic signature verification process during package layering operations. This flaw represents a critical weakness in the software update mechanism of containerized and atomic operating systems that rely on rpm-ostree for package management and deployment. The vulnerability stems from insufficient GPG signature validation procedures that should ensure package integrity and authenticity before installation. When packages are layered onto base images, the system should verify that each package bears a valid GPG signature from a trusted key, but this verification process was found to be inadequate in affected versions, potentially allowing malicious or corrupted packages to bypass security checks.
The technical implementation flaw occurs during the package layering process where rpm-ostree fails to properly validate GPG signatures on packages that are being added to existing base images. This weakness creates a scenario where unsigned packages or packages with invalid signatures may be accepted and installed without proper authentication. The vulnerability is particularly concerning in containerized environments and atomic operating systems where package integrity is paramount for system security and stability. The flaw allows for a form of code injection or package tampering where malicious actors could potentially introduce unauthorized software into systems that rely on rpm-ostree for package management. This represents a violation of the principle of least privilege and undermines the security model of atomic deployments where system updates should be cryptographically verified before application.
The operational impact of this vulnerability extends beyond simple package installation failures, potentially compromising the entire security posture of systems running affected versions of rpm-ostree. In environments where atomic updates are critical for maintaining system integrity, such as RHEL Atomic Host deployments, this vulnerability creates a window of opportunity for attackers to inject malicious code or corrupted packages that could lead to system compromise. The vulnerability affects systems that depend on layered package management, where base images are supplemented with additional packages through the layering mechanism. This issue particularly impacts enterprise environments where automated deployment pipelines rely on rpm-ostree for consistent and secure package management across multiple systems. The potential for privilege escalation and unauthorized system modification increases significantly when signature validation is bypassed, as it removes a crucial security control in the update process.
While the vulnerability presents significant risks, it is partially mitigated in RHEL Atomic Host environments through the implementation of certificate pinning as a default security measure. This mitigation strategy provides an additional layer of protection by restricting the acceptable certificates to a predefined set, thereby reducing the attack surface even when the primary GPG signature validation fails. Organizations should consider this partial mitigation as a temporary measure while implementing proper patching procedures to address the root cause. The certificate pinning approach aligns with security best practices outlined in the CWE database, specifically addressing weaknesses related to cryptographic failures and improper certificate validation. System administrators should implement comprehensive monitoring to detect unauthorized package installations and maintain detailed audit logs of package layering activities to identify potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under privilege escalation and execution techniques, where adversaries could leverage the signature bypass to gain unauthorized access to systems through compromised package installations. Remediation efforts must include immediate deployment of patched rpm-ostree versions, implementation of additional verification mechanisms, and comprehensive security reviews of existing package repositories to ensure no compromised packages have been installed.