COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONLive MITRE record

CAPEC-14

Client-side Injection-induced Buffer Overflow

This type of attack exploits a buffer overflow vulnerability in targeted client software through injection of malicious content from a custom-built hostile service. This hostile service is created to deliver the correct content to the client software. For example, if the client-side application is a browser, the service will host a webpage that the browser loads.

Abstraction

Detailed

Typical severity

High

Likelihood of attack

Medium

Understand the attack

What is this attack pattern?

This type of attack exploits a buffer overflow vulnerability in targeted client software through injection of malicious content from a custom-built hostile service. This hostile service is created to deliver the correct content to the client software. For example, if the client-side application is a browser, the service will host a webpage that the browser loads.

Execution flow

How does the attack proceed, step by step?

1

Explore

Identify target client-side application

The adversary identifies a target client-side application to perform the buffer overflow on. The most common are browsers. If there is a known browser vulnerability an adversary could target that.
2

Experiment

Find injection vector

The adversary identifies an injection vector to deliver the excessive content to the targeted application's buffer.

Techniques used

  • Many times client side applications will be open source, so an adversary can examine the source code to identify possible injection vectors.
  • Examine APIs of the client-side application and look for areas where a buffer overflow might be possible.

Create hostile service

The adversary creates a hostile service that will deliver content to the client-side application. If the intent is to simply cause the software to crash, the content need only consist of an excessive quantity of random data. If the intent is to leverage the overflow for execution of arbitrary code, the adversary crafts the payload in such a way that the overwritten return address is replaced with one of the adversary's choosing.

Techniques used

  • If the client-side application is a browser, the adversary will create a service that delivers a malicious webpage to the browser.
  • Create malicious shellcode that will execute when the program execution is returned to it.
  • Use a NOP-sled in the overflow content to more easily "slide" into the malicious code. This is done so that the exact return address need not be correct, only in the range of all of the NOPs
3

Exploit

Overflow the buffer

Using the injection vector, the adversary delivers the content to the client-side application using the hostile service and overflows the buffer.

Techniques used

  • If the adversary is targeting a local client-side application, they just need to use the service themselves.
  • If the adversary is attempting to cause an overflow on an external user's client-side application, they must get the user to attach to their service by some other means. This could be getting a user to visit their hostile webpage to target a user's browser.

Requirements

What does the attack require?

Prerequisites

  • The targeted client software communicates with an external server.
  • The targeted client software has a buffer overflow vulnerability.

Skills required

  • Low: To achieve a denial of service, an attacker can simply overflow a buffer by inserting a long string into an attacker-modifiable injection vector.
  • High: Exploiting a buffer overflow to inject malicious code into the stack of a software system or even the heap requires a more in-depth knowledge and higher skill level.

Resources required

Not stated in the MITRE record.

Detection

What are the indicators of the attack?

An example of indicator is when the client software crashes after executing code downloaded from a hostile server.

Impact

What does a successful attack lead to?

Read Data

Affected scopes: Confidentiality

Modify Data

Affected scopes: Integrity

Resource Consumption

Affected scopes: Availability

Execute Unauthorized Commands

Affected scopes: Confidentiality, Integrity, Availability

Defence

How is it prevented and mitigated?

1
The client software should not install untrusted code from a non-authenticated server.
2
The client software should have the latest patches and should be audited for vulnerabilities before being used to communicate with potentially hostile servers.
3
Perform input validation for length of buffer inputs.
4
Use a language or compiler that performs automatic bounds checking.
5
Use an abstraction library to abstract away risky APIs. Not a complete solution.
6
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.
7
Ensure all buffer uses are consistently bounds-checked.
8
Use OS-level preventative functionality. Not a complete solution.

Real world

MITRE example instances

Example instance 1Detail
Authors often use <EMBED> tags in HTML documents. For example <EMBED TYPE="audio/midi" SRC="/path/file.mid" AUTOSTART="true"> In Internet Explorer 4.0 an adversary attacker supplies an overly long path in the SRC= directive, the mshtml.dll component will suffer a buffer overflow. This is a standard example of content in a Web page being directed to exploit a faulty module in the system. There are potentially thousands of different ways data can propagate into a given system, thus these kinds of attacks will continue to be found in the wild.