CVE-2012-3867 in Puppet
Summary
by MITRE
lib/puppet/ssl/certificate_authority.rb in Puppet before 2.6.17 and 2.7.x before 2.7.18, and Puppet Enterprise before 2.5.2, does not properly restrict the characters in the Common Name field of a Certificate Signing Request (CSR), which makes it easier for user-assisted remote attackers to trick administrators into signing a crafted agent certificate via ANSI control sequences.
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Analysis
by VulDB Data Team • 12/07/2021
The vulnerability described in CVE-2012-3867 resides within the certificate authority implementation of Puppet configuration management software, specifically in the lib/puppet/ssl/certificate_authority.rb file. This flaw affects versions prior to 2.6.17 and 2.7.18 for the standard Puppet distribution, as well as Puppet Enterprise versions before 2.5.2. The issue stems from insufficient validation of the Common Name field within Certificate Signing Requests, creating a security weakness that can be exploited through manipulation of ANSI control sequences.
The technical flaw manifests in the improper restriction of characters within the Common Name field of Certificate Signing Requests, allowing attackers to embed ANSI control sequences that can manipulate terminal displays. These control sequences, which are typically used for formatting text in terminal environments, can be strategically placed within the Common Name field to create misleading visual representations when administrators review certificate requests. The vulnerability specifically targets the certificate authority's validation process, where it fails to properly sanitize or validate the input characters, particularly those that could alter display behavior in terminal interfaces.
The operational impact of this vulnerability is significant as it enables user-assisted remote attackers to craft malicious certificate requests that appear legitimate to administrators during the certificate signing process. When system administrators review certificate requests in terminal environments, the embedded ANSI control sequences can modify the display of the Common Name field, potentially concealing malicious intent or presenting misleading information about the entity requesting the certificate. This manipulation can lead to administrators unknowingly signing certificates for unintended purposes, effectively enabling man-in-the-middle attacks or unauthorized certificate issuance within the Puppet infrastructure.
This vulnerability aligns with CWE-174, which addresses the weakness of insufficient control of character sequences, and relates to the broader category of input validation flaws that can be exploited through character manipulation. From an ATT&CK framework perspective, this vulnerability maps to T1556.004 - "Modify Authentication Process" and potentially T1059.007 - "Command and Scripting Interpreter: JavaScript" when considering the terminal manipulation aspects. The attack vector requires administrator interaction during certificate signing operations, making it a user-assisted remote attack that leverages social engineering elements combined with technical exploitation.
The recommended mitigation strategy involves upgrading to patched versions of Puppet software, specifically version 2.6.17 or later for the 2.6.x series, 2.7.18 or later for the 2.7.x series, and Puppet Enterprise 2.5.2 or later. Organizations should also implement additional validation measures for certificate requests, including enhanced monitoring of certificate authority operations and implementing automated checks for suspicious character sequences. System administrators should be trained to recognize potential display manipulation techniques and verify certificate details through multiple independent verification methods rather than relying solely on visual inspection of terminal displays. Additionally, organizations should consider implementing certificate request approval workflows that include automated validation of Common Name fields against known good patterns and established naming conventions to prevent similar character manipulation attacks.