Detecting Exploit Code Execution in Loadable Kernel Modules
Detecting Exploit Code Execution in Loadable Kernel Modules HaizhiXu WenliangDu SteveJ.Chapin Systems Assurance Institute Syracuse University 3-114 CST, 111 College Place, Syracuse, NY 13210, USA g fhxu02, wedu, chapin @syr.edu Abstract and pointer checks can lead to kernel-level exploits, which can jeopardize the integrity of the running kernel. Inside the In current extensible monolithic operating systems, load- kernel, exploitcode has the privilegeto interceptsystem ser- able kernel modules (LKM) have unrestricted access to vice routines, to modify interrupt handlers, and to overwrite all portions of kernel memory and I/O space. As a result, kernel data. In such cases, the behavior of the entire sys- kernel-module exploitation can jeopardize the integrity of tem may become suspect. the entire system. In this paper, we analyze the threat that Kernel-level protection is different from user space pro- comes from the implicit trust relationship between the oper- tection. Not every application-level protection mechanism ating system kernel and loadable kernel modules. We then can be applied directly to kernel code, because privileges present a specification-directed access monitoring tool— of the kernel environment is different from that of the user HECK, that detects kernel modules for malicious code ex- space. For example, non-executableuser page [21] and non- ecution. Inside the module, HECK prevents code execution executable user stack [29] use virtual memory mapping sup- on the kernel stack and the data sections; on the bound- port for pages and segments, but inside the kernel, a page ary, HECK restricts the module’s access to only those kernel or segment fault can lead to kernel panic.
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