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From debugging to exploiting

Secure Code

Article from ADMIN 25/2015

By Toni Castillo Girona

Kernel and compiler security techniques, together with sound programming practices, fend off memory corruption exploits.

A number of modern protections are used to make software a bit more secure. Some of these are kernel based, whereas others are compiler based. In this article, I present a proof of concept capable of bypassing protections and exploiting code.

Many published papers have focused on the exploitation of ELF (executable and linkable format) binaries – a Linux standard file format – which bypasses modern protection techniques. (Table 1 lists a few techniques discussed in this article.) However, in some scenarios in which security has not historically been in the forefront, these protections are never applied, or, if so, the software holds many flaws that can still lead to a successful exploitation.

Table 1

Security Techniques

Acronym	Method
ASLR	Address space layout randomization
NX/DEP	No-execute bit/data execution prevention
RELRO	Relocation read-only
SSP	Stack smashing protector
PIE	Position-independent executable