CVE-2014-1876 in Java SE
Summary
by MITRE
The unpacker::redirect_stdio function in unpack.cpp in unpack200 in OpenJDK 6, 7, and 8; Oracle Java SE 5.0u61, 6u71, 7u51, and 8; JRockit R27.8.1 and R28.3.1; and Java SE Embedded 7u51 does not securely create temporary files when a log file cannot be opened, which allows local users to overwrite arbitrary files via a symlink attack on /tmp/unpack.log.
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Analysis
by VulDB Data Team • 06/17/2021
The vulnerability described in CVE-2014-1876 represents a critical security flaw in the Java runtime environment that affects multiple versions of OpenJDK and Oracle Java SE implementations. This issue stems from improper handling of temporary file creation during the unpacking process, specifically within the unpacker::redirect_stdio function located in unpack.cpp. The flaw occurs when the system attempts to redirect standard input/output streams but fails to properly secure temporary file creation when log file operations cannot be completed successfully. This vulnerability falls under the category of insecure temporary file handling as classified by CWE-377, which specifically addresses the creation of temporary files with insecure permissions or predictable names that can be exploited by malicious actors.
The technical exploitation of this vulnerability relies on a symlink attack mechanism that takes advantage of predictable temporary file paths and insecure file creation practices. When the unpack200 utility encounters a situation where it cannot open or write to the designated log file at /tmp/unpack.log, the system creates temporary files without proper security measures. Attackers can manipulate this process by creating a symbolic link at the expected temporary file location that points to a target file they wish to overwrite. This type of attack pattern aligns with the ATT&CK technique T1552.001, which covers "Unsecured Credentials" through the manipulation of temporary files and symbolic links. The vulnerability is particularly dangerous because it allows local users to escalate privileges and overwrite arbitrary files on the system, potentially leading to privilege escalation or data corruption.
The operational impact of this vulnerability extends across multiple Java implementations and versions, making it a widespread concern for system administrators and security professionals. The affected products include OpenJDK 6, 7, and 8, Oracle Java SE 5.0u61, 6u71, 7u51, and 8, JRockit R27.8.1 and R28.3.1, and Java SE Embedded 7u51, indicating that the flaw exists across different Java runtime environments and versions. This broad impact means that organizations running any of these Java versions are potentially vulnerable to this attack vector, particularly in environments where local users might have limited access to system resources but can still manipulate symbolic links. The vulnerability can be exploited by attackers who have local access to the system, making it particularly concerning in multi-user environments where privilege separation is not properly enforced.
Mitigation strategies for CVE-2014-1876 should focus on addressing the root cause of insecure temporary file creation and implementing proper file access controls. Organizations should immediately apply security patches and updates from Oracle and OpenJDK maintainers to resolve this vulnerability. System administrators should also implement proper file permissions and access controls to prevent unauthorized symbolic link creation in temporary directories. The recommended approach includes ensuring that temporary files are created with secure permissions, using unique and unpredictable naming conventions, and implementing proper file descriptor management. Additionally, organizations should consider implementing monitoring and alerting mechanisms to detect suspicious symbolic link creation activities in temporary directories. This vulnerability demonstrates the importance of secure coding practices and proper input validation in system components that handle file operations, aligning with the security principles outlined in the OWASP Top Ten and other industry security frameworks that emphasize secure temporary file handling as a fundamental security control.