CVE-2017-17878 in Steam Link
Summary
by MITRE
An issue was discovered in Valve Steam Link build 643. Root passwords longer than 8 characters are truncated because of the default use of DES (aka the CONFIG_FEATURE_DEFAULT_PASSWD_ALGO="des" setting).
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Analysis
by VulDB Data Team • 01/19/2023
The vulnerability identified as CVE-2017-17878 resides within Valve Steam Link software version 643, specifically addressing a critical weakness in password handling mechanisms. This issue stems from the software's default configuration that employs the Data Encryption Standard algorithm for password hashing, a legacy approach that fundamentally limits password security. The root cause of this vulnerability is the intentional truncation of root passwords exceeding eight characters, a behavior directly attributed to the DES-based hashing implementation. This design choice creates a significant security gap where any password longer than eight characters is effectively reduced to its first eight characters during the hashing process, thereby undermining the intended security provided by longer passwords.
The technical flaw manifests through the CONFIG_FEATURE_DEFAULT_PASSWD_ALGO="des" setting which governs how passwords are processed within the Steam Link environment. This particular algorithmic choice represents a known weakness in cryptographic security practices, as DES was designed for a different era of computing and lacks the computational complexity required to adequately protect modern password systems. The truncation behavior creates a predictable vulnerability where attackers can exploit the reduced password length to perform more effective brute force or dictionary attacks, as the effective entropy of the password is significantly diminished. This weakness directly violates fundamental security principles and aligns with CWE-326, which addresses the use of weak encryption algorithms, and CWE-762, which covers the use of hardcoded passwords.
The operational impact of this vulnerability extends beyond simple password truncation, creating a substantial risk for users who rely on longer, more complex passwords for system security. Attackers can exploit this weakness by focusing their efforts on the first eight characters of any password, dramatically reducing the computational resources required to crack the system. The vulnerability affects all users of Steam Link build 643 who have configured root passwords exceeding eight characters, potentially allowing unauthorized access to system resources and user data. This weakness creates opportunities for privilege escalation attacks and represents a significant risk to system integrity and user privacy, particularly in environments where the Steam Link device serves as a gateway to other networked systems.
Mitigation strategies for this vulnerability require immediate attention through configuration changes that disable the problematic DES-based password hashing and implement stronger cryptographic algorithms. System administrators should update the CONFIG_FEATURE_DEFAULT_PASSWD_ALGO setting to utilize more secure hashing mechanisms such as SHA-512 or bcrypt, which provide adequate entropy preservation for passwords of any length. The recommended approach involves modifying the software configuration to ensure that password truncation no longer occurs, thereby maintaining the full security strength of user-created passwords. Additionally, organizations should enforce password policies that require strong, complex passwords while ensuring that the underlying system configuration supports these requirements through proper cryptographic implementation. This remediation aligns with ATT&CK technique T1212, which addresses the exploitation of system configuration weaknesses, and emphasizes the need for proper cryptographic security controls in embedded systems and networked devices.