CVE-2003-0094 in util-linux
Summary
by MITRE
A patch for mcookie in the util-linux package for Mandrake Linux 8.2 and 9.0 uses /dev/urandom instead of /dev/random, which causes mcookie to use an entropy source that is more predictable than expected, which may make it easier for certain types of attacks to succeed.
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Analysis
by VulDB Data Team • 04/23/2019
The vulnerability described in CVE-2003-0094 relates to the mcookie utility within the util-linux package on Mandrake Linux versions 8.2 and 9.0. This utility is designed to generate random cookie values for X11 authentication purposes, which are critical for securing graphical user interface sessions. The flaw stems from a change in the entropy source used by the mcookie utility during its patch implementation, specifically switching from /dev/random to /dev/urandom. This change represents a significant security regression because /dev/random is designed to provide cryptographically secure random numbers by blocking when entropy is low, whereas /dev/urandom provides non-blocking random data that may be less secure for cryptographic purposes. The vulnerability falls under CWE-330 Use of Insufficiently Random Values, which directly addresses weaknesses in the generation of random numbers that are insufficiently unpredictable for cryptographic use cases. The operational impact of this vulnerability is substantial as it weakens the security of X11 authentication mechanisms, potentially enabling attackers to predict cookie values and gain unauthorized access to graphical sessions. This weakness aligns with ATT&CK technique T1552.001 for Unsecured Credentials and T1078.002 for Valid Accounts, as compromised X11 cookies could allow lateral movement and privilege escalation within graphical environments. The security implications extend beyond simple authentication bypasses, as predictable random values can undermine the entire security model of X11 windowing system authentication protocols. This vulnerability demonstrates the critical importance of entropy sources in cryptographic implementations and how seemingly minor changes in system utilities can have significant security consequences. The use of /dev/urandom instead of /dev/random in this context creates a predictable attack surface that adversaries could exploit to perform session hijacking or authentication spoofing attacks against X11 graphical interfaces. Organizations using affected Mandrake Linux versions should immediately apply security patches that restore the use of /dev/random or implement alternative entropy sources to ensure that mcookie generates sufficiently random values for secure X11 authentication. The vulnerability also highlights the need for comprehensive security testing of system utilities, particularly those involved in authentication and credential management, to prevent such regressions in cryptographic security implementations. This issue represents a classic example of how entropy management can become a critical security concern in operating system components that are often overlooked in traditional security assessments.