COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONLive MITRE record

CAPEC-9

Buffer Overflow in Local Command-Line Utilities

This attack targets command-line utilities available in a number of shells. An adversary can leverage a vulnerability found in a command-line utility to escalate privilege to root.

Abstraction

Detailed

Typical severity

High

Likelihood of attack

High

Understand the attack

What is this attack pattern?

This attack targets command-line utilities available in a number of shells. An adversary can leverage a vulnerability found in a command-line utility to escalate privilege to root.

Execution flow

How does the attack proceed, step by step?

Explore

Identify target system

The adversary first finds a target system that they want to gain elevated priveleges on. This could be a system they already have some level of access to or a system that they will gain unauthorized access at a lower privelege using some other means.

Find injection vector

The adversary identifies command line utilities exposed by the target host that contain buffer overflow vulnerabilites. The adversary likely knows which utilities have these vulnerabilities and what the effected versions are, so they will also obtain version numbers for these utilities.

Experiment

Craft overflow command

Once the adversary has found a vulnerable utility, they will use their knownledge of the vulnerabilty to create the command that will exploit the buffer overflow.

Exploit

Overflow the buffer

Using the injection vector, the adversary executes the crafted command, gaining elevated priveleges on the machine.

Requirements

What does the attack require?

Prerequisites

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.

Skills required

Low: An adversary can simply overflow a buffer by inserting a long string into an adversary-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.

Resources required

Not stated in the MITRE record.

Impact

What does a successful attack lead to?

Gain Privileges

Affected scopes: Confidentiality, Access Control, Authorization

Execute Unauthorized Commands

Affected scopes: Confidentiality, Integrity, Availability

Modify Data

Affected scopes: Integrity

Unreliable Execution

Affected scopes: Availability

Read Data

Affected scopes: Confidentiality

Defence

How is it prevented and mitigated?

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, especially against a zero day attack.

Do not unnecessarily expose services.

Real world

MITRE example instances

Example instance 1Detail

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[0].