CVE-2017-15288 in Scala
Summary
by MITRE
The compilation daemon in Scala before 2.10.7, 2.11.x before 2.11.12, and 2.12.x before 2.12.4 uses weak permissions for private files in /tmp/scala-devel/${USER:shared}/scalac-compile-server-port, which allows local users to write to arbitrary class files and consequently gain privileges.
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Analysis
by VulDB Data Team • 01/10/2023
The vulnerability identified as CVE-2017-15288 affects the Scala compilation daemon across multiple versions including 2.10.7, 2.11.12, and 2.12.4, presenting a significant security risk through improper file permission handling within the temporary directory structure. This issue resides in the Scala development environment's compilation server mechanism that creates temporary files with insufficient access controls, creating a pathway for privilege escalation attacks. The affected directory structure /tmp/scala-devel/${USER:shared}/scalac-compile-server-port demonstrates a clear lack of proper sandboxing and access control mechanisms that should be implemented in temporary file handling operations. The vulnerability specifically targets the weak permissions assigned to private files within the Scala compilation daemon's temporary storage area, where the system fails to properly restrict access to these critical temporary files that contain compilation artifacts and server communication data.
The technical flaw manifests through the compilation daemon's failure to implement proper file system permissions for temporary files that are created during the compilation process. When Scala's compilation daemon initializes, it generates temporary files in the designated /tmp/scala-devel directory structure, but these files are created with overly permissive access controls that allow local users to modify or overwrite critical class files. This weakness stems from the daemon's assumption that only authorized processes can access these temporary files, failing to account for the possibility of privilege escalation through local file system manipulation. The attack vector leverages the fact that the daemon creates files with world-writable permissions or insufficient user-specific access controls, enabling malicious local users to inject arbitrary code into the compilation process. The vulnerability operates at the intersection of file system security and application-level privilege management, where the compilation daemon fails to properly isolate temporary files from unauthorized access by other users on the same system.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential code injection and execution capabilities within the Scala development environment. Local attackers can exploit this weakness to overwrite legitimate class files with malicious code, potentially leading to arbitrary code execution with the privileges of the Scala compilation daemon process. This creates a significant risk for development environments where multiple users share the same system, as the vulnerability allows an unprivileged user to compromise the integrity of the compilation process and potentially gain elevated privileges. The attack scenario involves creating malicious class files that are subsequently loaded and executed by the Scala compiler, effectively bypassing normal security boundaries. This vulnerability directly impacts the security posture of development workstations and continuous integration systems where Scala compilation occurs, as it provides a persistent attack vector that can be exploited repeatedly without requiring network access or external exploitation techniques. The implications are particularly severe in enterprise environments where development systems may be shared or where the compilation daemon runs with elevated privileges.
Mitigation strategies for CVE-2017-15288 should focus on immediate version upgrades to patched releases of Scala, specifically versions 2.10.7, 2.11.12, and 2.12.4, which address the weak file permission handling issue. System administrators should implement proper file system permissions for temporary directories, ensuring that temporary files created by the Scala compilation daemon are created with restrictive access controls that prevent unauthorized modification. The recommended approach includes configuring the temporary directory with proper umask settings and implementing access control lists that restrict file access to the specific user or process that created the files. Organizations should also consider implementing additional security controls such as file system monitoring to detect unauthorized modifications to temporary files and regular audits of the temporary directory structures. The vulnerability aligns with CWE-732, which addresses inadequate permissions for critical resources, and represents a clear violation of the principle of least privilege. From an ATT&CK perspective, this vulnerability maps to privilege escalation techniques through file system manipulation and can be categorized under T1068, which covers exploit for privilege escalation, making it a critical concern for security teams implementing comprehensive threat hunting and incident response procedures.