CVE-2014-3227 in dpkg
Summary
by MITRE
dpkg 1.15.9, 1.16.x before 1.16.14, and 1.17.x before 1.17.9 expect the patch program to be compliant with a need for the "C-style encoded filenames" feature, but is supported in environments with noncompliant patch programs, which triggers an interaction error that allows remote attackers to conduct directory traversal attacks and modify files outside of the intended directories via a crafted source package. NOTE: this vulnerability exists because of reliance on unrealistic constraints on the behavior of an external program.
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Analysis
by VulDB Data Team • 05/17/2018
The vulnerability identified as CVE-2014-3227 resides within the dpkg package management system, specifically affecting versions 1.15.9 and various 1.16.x releases prior to 1.16.14, as well as 1.17.x versions before 1.17.9. This issue stems from dpkg's improper handling of external program dependencies, particularly the patch utility, which creates a dangerous reliance on unrealistic constraints for external tool behavior. The flaw manifests when dpkg attempts to process source packages that contain filenames requiring C-style encoding, a feature that the patch program must support for proper operation. However, the system fails to adequately validate or handle environments where the patch utility does not conform to these expected behaviors, creating a critical security gap.
The technical implementation of this vulnerability exploits the interaction between dpkg's internal file handling mechanisms and external patch program functionality. When processing a crafted source package, dpkg's reliance on the patch utility's compliance with C-style encoded filenames creates a scenario where malformed input can cause the patch program to execute commands outside of intended directories. This occurs because dpkg's directory traversal protection mechanisms are bypassed when the external patch utility fails to properly handle the encoding requirements, allowing attackers to manipulate file paths through carefully crafted source package contents. The vulnerability essentially transforms what should be a controlled package installation process into a potential vector for arbitrary file modification.
The operational impact of CVE-2014-3227 extends beyond simple directory traversal, as it enables remote attackers to execute arbitrary file modifications on systems running vulnerable dpkg versions. This capability allows adversaries to overwrite critical system files, inject malicious code into package installations, or manipulate the package management database itself. The vulnerability is particularly dangerous in automated deployment environments where package installations occur without manual oversight, as it can silently compromise system integrity. The attack vector requires remote access to a system capable of processing malicious source packages, making it a significant concern for package repositories, build servers, and automated deployment systems that handle untrusted package content.
Security mitigations for this vulnerability involve updating to patched versions of dpkg where versions 1.16.14 and 1.17.9 or later provide proper handling of external program dependencies. Organizations should implement strict package validation procedures for source packages, particularly those from untrusted sources, and consider isolating package building processes in restricted environments. The vulnerability aligns with CWE-22 directory traversal weaknesses and can be mapped to ATT&CK techniques involving privilege escalation and persistence through package management manipulation. System administrators should also monitor for unauthorized package installations and implement proper access controls to limit who can introduce packages into systems. The fundamental issue represents a classic case of over-reliance on external tool behavior, highlighting the importance of defensive programming practices that account for external dependency variations in security-critical applications.