CVE-2018-20510 in Linux
Summary
by MITRE
The print_binder_transaction_ilocked function in drivers/android/binder.c in the Linux kernel 4.14.90 allows local users to obtain sensitive address information by reading "*from *code *flags" lines in a debugfs file.
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Analysis
by VulDB Data Team • 09/11/2023
The vulnerability identified as CVE-2018-20510 resides within the Linux kernel's Android binder driver implementation, specifically in the print_binder_transaction_ilocked function located in drivers/android/binder.c. This issue affects kernel versions up to 4.14.90 and represents a significant information disclosure weakness that could potentially be exploited by local attackers to gain insights into kernel memory layouts and address spaces. The vulnerability manifests through the debugfs interface where sensitive address information is inadvertently exposed during transaction processing operations.
The technical flaw stems from improper handling of debug information within the binder transaction mechanism that governs inter-process communication in Android systems. When the print_binder_transaction_ilocked function processes transaction data, it writes debugging information containing memory addresses to debugfs files without adequate sanitization. The specific exposure occurs in the "from code *flags" line outputs that contain pointers and address values from kernel memory regions. These addresses, when accessible to unprivileged local users, can reveal information about kernel virtual memory layout and potentially aid in more sophisticated exploitation techniques.
The operational impact of this vulnerability extends beyond simple information disclosure as it provides attackers with valuable kernel address information that could be leveraged in subsequent exploitation attempts. Local users who can access the debugfs interface can read these exposed addresses and use them to bypass kernel address space layout randomization protections or to craft more targeted attacks. This vulnerability particularly affects Android-based systems where the binder driver serves as the primary IPC mechanism between applications and system services, making it a critical component for attackers seeking to escalate privileges or gain deeper system access.
This vulnerability maps to CWE-200, which covers "Information Exposure," and aligns with several ATT&CK techniques including T1059 for command and scripting interpreter and T1068 for exploit for privilege escalation. The exposure of kernel addresses through debugfs interfaces represents a classic example of insufficient output sanitization that can be exploited by attackers to gather intelligence for more advanced attacks. Organizations running affected kernel versions should prioritize patching to address this information disclosure vulnerability, as it could serve as a stepping stone for more serious security breaches. The vulnerability highlights the importance of proper access controls and output sanitization in kernel subsystems, particularly those exposed through debug interfaces that may be accessible to unprivileged users.
The remediation approach involves applying the kernel patch that properly sanitizes the debug output in the print_binder_transaction_ilocked function and restricts access to debugfs interfaces containing sensitive kernel information. System administrators should also implement proper access controls to debugfs filesystems and consider disabling unnecessary debug interfaces in production environments. The vulnerability demonstrates the critical need for security reviews of kernel debug interfaces and proper privilege separation to prevent local users from accessing potentially sensitive kernel information through seemingly benign debugging output mechanisms.