This attack targets libraries or shared code modules which are vulnerable
to buffer overflow attacks. An attacker who has access to an API may try to
embed malicious code in the API function call and exploit a buffer overflow
vulnerability in the function's implementation. All clients that make use of
the code library thus become vulnerable by association. This has a very
broad effect on security across a system, usually affecting more than one
software process.
Attack Execution Flow
An attacker can call an API exposed by the target
host.
On the probing stage, the attacker injects
malicious code using the API call and observes the
results. The attacker's goal is to uncover a buffer
overflow vulnerability.
The attacker finds a buffer overflow
vulnerability, crafts malicious code and injects it
through an API call. The attacker can at worst
execute remote code on the target host.
Attack Prerequisites
The target host exposes an API to the user.
One or more API functions exposed by the target host has a buffer overflow
vulnerability.
Typical Likelihood of Exploit
Likelihood: High
Methods of Attack
API Abuse
Injection
Examples-Instances
Description
A buffer overflow in the FreeBSD utility setlocale (found in the libc
module) puts many programs at risk all at once.
Description
A buffer overflow in the Xt library of the X windowing system allows
local users to execute commands with root privileges.
Attacker Skills or Knowledge Required
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.
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.
Solutions and Mitigations
Use a language or compiler that performs automatic bounds checking.
Use secure functions not vulnerable to buffer overflow.
If you have to use dangerous functions, make sure that you do boundary
checking.
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.
Use OS-level preventative functionality. Not a complete solution.
Attack Motivation-Consequences
Scope
Technical Impact
Note
Availability
DoS: crash / exit /
restart
Confidentiality
Integrity
Availability
Execute unauthorized code or
commands
Confidentiality
Read memory
Integrity
Modify memory
Injection Vector
The user supplied data.
Payload
The buffer overrun by the attacker.
Activation Zone
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.
Description
