Common Attack Pattern Enumeration and Classification
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This type of attack exploits a buffer overflow vulnerability in targeted client software through injection of malicious content from a custom-built hostile service.
Attack Execution Flow
The targeted client software communicates with an external server.
The targeted client software has a buffer oveflow vulnerability.
Authors often use <EMBED> tags in HTML documents. For example
<EMBED TYPE="audio/midi" SRC="/path/file.mid" AUTOSTART="true">
If an 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.
Skill or Knowledge Level: 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.
Skill or Knowledge Level: 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.
The server may look like a valid server, but in reality it may be a hostile server aimed at fooling the client software. For instance the server can use honey pots and get the client to download malicious code.
Once engaged with the client, the hostile server may attempt to scan the client's host for open ports and potential vulnerabilities in the client software.
The hostile server may also attempt to install and run malicious code on the client software. That malicious code can be used to scan the client software for buffer overflow.
An example of indicator is when the client software crashes after executing code downloaded from a hostile server.
The client software should not install untrusted code from a non authenticated server.
The client software should have the latest patches and should be audited for vulnerabilities before being used to communicate with potentially hostile servers.
Perform input validation for length of buffer inputs.
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.
Ensure all buffer uses are consistently bounds-checked.
Use OS-level preventative functionality. Not a complete solution.
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 malicious code.
[R.14.1] [REF-2] G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. February 2004.