Common Attack Pattern Enumeration and Classification
A Community of Knowledge Resource for Building Secure Software
This attack targets command-line utilities available in a number of shells. An attacker can leverage a vulnerability found in a command-line utility to escalate privilege to root.
Attack Execution Flow
The target host exposes a command-line utility to the user.
The command-line utility exposed by the target host has a buffer overflow vulnerability that can be exploited.
Attack Example: HPUX passwd
A buffer overflow in the HPUX passwd command allows local users to gain root privileges via a command-line option.
Attack Example: Solaris getopt
A buffer overflow in Solaris's getopt command (found in libc) allows local users to gain root privileges via a long argv.
Skill or Knowledge Level: Low
An attacker can simply overflow a buffer by inserting a long string into an attacker-modifiable injection vector. The result can be a DoS.
Skill or Knowledge Level: High
Exploiting a buffer overflow to inject malicious code into the stack of a software system or even the heap can require a higher skill level.
The attacker can probe for services available on the target host. Many services may expose a command utility. For instance Telnet is a service which can be invoked through a command shell.
Carefully review the service's implementation before making it available to user. For instance you can use manual or automated code review to uncover vulnerabilities such as buffer overflow.
Use a language or compiler that performs automatic bounds checking.
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Compiler-based canary mechanisms such as StackGuard, ProPolice and the Microsoft Visual Studio /GS flag. Unless this provides automatic bounds checking, it is not a complete solution.
Operational: Use OS-level preventative functionality. Not a complete solution.
Apply the latest patches to your user exposed services. This may not be a complete solution, specially against zero day attack.
Do not unnecessarily expose services.
When the function returns control to the main program, it jumps to the return address portion of the stack frame. Unfortunately that return address may have been overwritten by the overflowed buffer and the address may contain a call to a privileged command or to a malicious code.
[R.9.1] [REF-2] G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. February 2004.