Technical Report (TR00-02) Cover Page

Department of Information Science, Faculty of Science, University of Tokyo

Title:

Exploiting Segmentation Mechanism for Protecting against Malicious Mobile Code

Authors:

Takahiro Shinagawa, Kenji Kono, and Takashi Masuda

Key words and phrases:

operating system, fine-grained protection domain, virtual memory, mobile code, security

Abstract:

This paper describes a mechanism for protecting against malicious mobile code. As mobile code is linked with a hosting application and executed in the same process, a fine-grained protection domain providing an intra-process protection is required to prevent a malicious mobile code from unauthorized access. This paper introduces a multi-protection page table: a mechanism of virtual memory that enables fine-grained protection domains to be supported at the kernel level. A fine-grained protection domain (1) confines the memory accesses by mobile code in authorized areas, (2) restricts the system calls issued by mobile code, and (3) enables efficient cross-domain calls among mobile codes and a hosting application. Efficiency of cross-domain calls encourages the use of fine-grained protection domains. This paper demonstrates that a multi-protection page table can be implemented efficiently on the most widely used architecture; that is, Intel x86 family. The presented implementation achieves reasonable performance for practical use; one round-trip cross-domain call requires 226 to 608 cycles. Experimental results show that the protection overhead is only 6.1% to 15.8% in a real application.

Report date:

May 17, 2000

Written language:

English

Total number of pages:

16

Number of references:

15

Any other identifying information of this report:

Submitted for publication

Distribution statement:

This technical report is available ONLY through http://www.is.s.u-tokyo.ac.jp/tech-reports/FILES.html.

Supplementary notes: