CVE-2011-3848 in Puppet
Summary
by MITRE
Directory traversal vulnerability in Puppet 2.6.x before 2.6.10 and 2.7.x before 2.7.4 allows remote attackers to write X.509 Certificate Signing Request (CSR) to arbitrary locations via (1) a double-encoded key parameter in the URI in 2.7.x, (2) the CN in the Subject of a CSR in 2.6 and 0.25.
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Analysis
by VulDB Data Team • 11/24/2021
The vulnerability identified as CVE-2011-3848 represents a critical directory traversal flaw affecting Puppet configuration management software versions 2.6.x prior to 2.6.10 and 2.7.x prior to 2.7.4. This vulnerability resides in the certificate handling mechanisms of Puppet's certificate authority functionality, specifically within how the software processes X.509 Certificate Signing Requests. The flaw manifests through two distinct attack vectors that exploit different aspects of the certificate generation process, creating a pathway for remote attackers to execute arbitrary file operations on the affected system. The vulnerability is classified under CWE-22, which specifically addresses directory traversal or path traversal conditions that allow attackers to access files and directories outside the intended scope.
The technical exploitation occurs through manipulation of key parameters in certificate requests, leveraging the software's insufficient input validation and sanitization mechanisms. In version 2.7.x, attackers can exploit a double-encoded key parameter within the URI to bypass normal path validation checks, while in versions 2.6 and 0.25, the vulnerability is accessible through manipulation of the Common Name (CN) field in the Subject section of Certificate Signing Requests. The underlying flaw stems from inadequate sanitization of user-supplied data before it is used in file system operations, allowing maliciously crafted certificate requests to specify arbitrary file paths that the system will attempt to write to. This represents a classic path traversal vulnerability where attacker-controlled input directly influences file system operations without proper validation of the intended destination.
The operational impact of this vulnerability is severe as it enables remote attackers to write files to arbitrary locations on the target system, potentially allowing for privilege escalation, data corruption, or system compromise. An attacker who successfully exploits this vulnerability could place malicious files in critical system directories, modify existing certificate files, or create backdoor access points through certificate manipulation. The attack surface is particularly concerning in environments where Puppet is used for managing security certificates and where the certificate authority is accessible over the network. This vulnerability directly impacts the integrity and confidentiality of the certificate management infrastructure, potentially allowing attackers to impersonate legitimate system components or intercept communications. The vulnerability aligns with ATT&CK technique T1552.001 for credential access and T1059.001 for command and scripting interpreter, as it enables attackers to establish persistent access through certificate manipulation.
Mitigation strategies for CVE-2011-3848 primarily focus on immediate version upgrades to patched releases of Puppet software, specifically moving to versions 2.6.10 or 2.7.4 and later. Organizations should also implement network segmentation to limit access to Puppet certificate authorities, ensuring that only trusted systems can submit certificate requests. Additional protective measures include implementing strict input validation on certificate request parameters, monitoring certificate authority logs for suspicious file creation patterns, and applying network-based intrusion detection systems to identify potential exploitation attempts. Security administrators should also review and restrict file system permissions on certificate authority directories to minimize the impact of successful exploitation attempts. The vulnerability highlights the importance of proper input sanitization and access control mechanisms in cryptographic systems, as well as the necessity of regular security updates and patch management processes to protect against known vulnerabilities in widely-used infrastructure software.