CVE-2017-12849 in SilverStripe
Summary
by MITRE
Response discrepancy in the login and password reset forms in SilverStripe CMS before 3.5.5 and 3.6.x before 3.6.1 allows remote attackers to enumerate users via timing attacks.
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Analysis
by VulDB Data Team • 11/24/2019
The vulnerability identified as CVE-2017-12849 represents a critical timing attack vulnerability affecting SilverStripe CMS versions prior to 3.5.5 and 3.6.x versions before 3.6.1. This issue stems from inconsistent response times between legitimate and non-existent user accounts during authentication and password reset operations, creating a window for attackers to systematically determine valid user accounts through careful observation of server response patterns. The vulnerability operates at the application logic level, specifically targeting the authentication mechanisms that fail to provide consistent response times regardless of whether a user account exists in the system.
The technical flaw manifests in the way SilverStripe handles user enumeration during login and password reset processes. When an attacker submits a username that does not exist in the system, the server response time differs significantly from when a valid username is submitted. This timing discrepancy occurs because the application performs different processing paths for valid versus invalid accounts, with valid accounts requiring additional database lookups and processing steps. The inconsistency in response times creates a timing side-channel attack vector that allows remote attackers to infer account existence through repeated requests and timing measurements. This vulnerability directly maps to CWE-203, which addresses "Information Exposure Through Discrepancy in Response Time," and falls under the broader category of timing attack vulnerabilities that exploit temporal variations in system behavior.
The operational impact of this vulnerability extends beyond simple user enumeration, potentially enabling more sophisticated attack vectors including account takeover attempts and credential stuffing attacks. Attackers can systematically test multiple usernames against the login and password reset endpoints, measuring response times to distinguish between valid and invalid accounts. Once a list of valid usernames is obtained, attackers can focus their efforts on password cracking or social engineering attacks against those specific accounts. The vulnerability affects both authentication and password reset functionality, amplifying its potential impact as attackers can exploit this weakness across multiple attack surfaces within the same application. This issue particularly impacts organizations using older SilverStripe versions where the security patch has not been applied, leaving them exposed to automated enumeration attacks that can be executed at scale.
Organizations should immediately implement the recommended security patches for SilverStripe CMS versions 3.5.5 and 3.6.1 to address this vulnerability. The fix involves ensuring that all authentication and password reset operations return consistent response times regardless of whether the user account exists, typically through implementing constant-time comparison algorithms and uniform processing paths for both valid and invalid inputs. Security teams should also consider implementing rate limiting and account lockout mechanisms to prevent automated enumeration attempts, while monitoring for unusual patterns in authentication requests that may indicate timing attack activity. Additionally, organizations should review their application logs for evidence of user enumeration attempts and implement proper intrusion detection systems that can identify and alert on suspicious authentication patterns. The vulnerability demonstrates the importance of applying security patches promptly and highlights the need for consistent security practices in authentication mechanisms to prevent timing side-channel attacks that can compromise user account security and system integrity.