CVE-2018-12477 in Open Build Service
Summary
by MITRE
A Improper Neutralization of CRLF Sequences vulnerability in Open Build Service allows remote attackers to cause deletion of directories by tricking obs-service-refresh_patches to delete them. Affected releases are openSUSE Open Build Service: versions prior to d6244245dda5367767efc989446fe4b5e4609cce.
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Analysis
by VulDB Data Team • 05/23/2023
The CVE-2018-12477 vulnerability represents a critical improper neutralization of CRLF (Carriage Return Line Feed) sequences flaw within the Open Build Service platform, specifically affecting the obs-service-refresh_patches component. This vulnerability exists in openSUSE Open Build Service versions prior to the commit hash d6244245dda5367767efc989446fe4b5e4609cce, creating a dangerous condition where remote attackers can manipulate directory deletion operations through carefully crafted input sequences. The issue stems from insufficient validation of input parameters that are processed by the refresh_patches service, which is responsible for managing patch updates within the build environment.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious input containing CRLF sequences that are not properly sanitized before being processed by the directory deletion mechanism. These sequences, typically represented as \r\n in ASCII format, can be injected into parameters that control directory operations within the build service. When the obs-service-refresh_patches component processes these inputs without proper neutralization, the CRLF characters can be interpreted as command terminators or parameter separators, allowing attackers to inject additional commands or manipulate the intended directory deletion behavior. This creates a path traversal and command injection scenario where the attacker can potentially delete arbitrary directories on the system where the Open Build Service is hosted.
The operational impact of this vulnerability extends beyond simple directory deletion, as it represents a fundamental security flaw in how the build service handles user input and processes directory operations. Attackers can leverage this vulnerability to compromise the integrity of the build environment by removing critical directories containing build scripts, source code repositories, or configuration files. The consequences can include complete build system disruption, data loss, and potential compromise of the entire software development pipeline. This vulnerability particularly affects organizations that rely on Open Build Service for automated software builds and package management, as it undermines the trust model of the build infrastructure and could lead to supply chain compromises.
Mitigation strategies for CVE-2018-12477 should focus on implementing proper input sanitization and neutralization of CRLF sequences throughout the obs-service-refresh_patches component. Organizations should upgrade to the patched version of Open Build Service that includes commit d6244245dda5367767efc989446fe4b5e4609cce or later, which addresses the improper neutralization issue. Additionally, implementing strict input validation mechanisms that filter out or escape CRLF sequences in all user-controllable parameters can prevent exploitation. Network segmentation and access controls should be enforced to limit exposure of the build service to untrusted users, while monitoring systems should be deployed to detect anomalous directory deletion patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-117, which addresses improper neutralization of special elements used in system commands, and maps to ATT&CK technique T1059.001 for command and scripting interpreter, specifically focusing on the execution of system commands through vulnerable input handling mechanisms.
The broader implications of this vulnerability highlight the importance of secure coding practices in build and automation systems, where input validation and sanitization are critical components of security. Organizations should conduct comprehensive security reviews of their build infrastructure and implement defense-in-depth strategies that include regular patch management, input validation, and monitoring of critical system operations. The vulnerability demonstrates how seemingly minor input handling flaws can lead to significant operational impacts in automated build environments, emphasizing the need for rigorous security testing of all components within the software development lifecycle.