COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONMITRE canlı kaydı

CAPEC-46

Overflow Variables and Tags

This type of attack leverages the use of tags or variables from a formatted configuration data to cause buffer overflow. The adversary crafts a malicious HTML page or configuration file that includes oversized strings, thus causing an overflow.

Soyutlama

Detailed

Tipik ciddiyet

High

Saldırı ihtimali

High

Saldırıyı anla

Bu saldırı kalıbı nedir?

Uygulama akışı

Saldırı adım adım nasıl ilerler?

Explore

Identify target application

The adversary identifies a target application or program to perform the buffer overflow on. Adversaries look for applications or programs that accept formatted files, such as configuration files, as input.

Experiment

Find injection vector

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

Kullanılan teknikler

Knowing the type of file that an application takes as input, the adversary takes a normal input file and modifies a single variable or tag to contain a large amount of data. If there is a crash, this means that a buffer overflow attack is possible. The adversary will keep changing single variables or tags one by one until they see a change in behavior.

Craft overflow content

The adversary crafts the content to be injected. 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.

Kullanılan teknikler

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

Exploit

Overflow the buffer

The adversary will upload the crafted file to the application, causing a buffer overflow.

Gereksinimler

Saldırının gerçekleşmesi için ne gerekir?

Ön koşullar

The target program consumes user-controllable data in the form of tags or variables.
The target program does not perform sufficient boundary checking.

Gerekli beceri

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.

Gerekli kaynak

MITRE kaydında belirtilmemiş.

Etki

Başarılı saldırı neye yol açar?

Unreliable Execution

Etkilenen alanlar: Availability

Execute Unauthorized Commands

Etkilenen alanlar: Confidentiality, Integrity, Availability

Read Data

Etkilenen alanlar: Confidentiality

Modify Data

Etkilenen alanlar: Integrity

Savunma

Nasıl önlenir ve etkisi azaltılır?

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.

Use OS-level preventative functionality. Not a complete solution.

Do not trust input data from user. Validate all user input.

Gerçek dünya

MITRE örnek olayları

Örnek olay 1Detay

A buffer overflow vulnerability exists in the Yamaha MidiPlug that can be accessed via a Text variable found in an EMBED tag. See also: CVE-1999-0946

Örnek olay 2Detay

A buffer overflow in Exim allows local users to gain root privileges by providing a long :include: option in a .forward file. See also: CVE-1999-0971