Difference between revisions of "Insecure Compiler Optimization"

From OWASP
Jump to: navigation, search
(Added contents provided by Fortify.)
Line 2: Line 2:
 
{{Template:Fortify}}
 
{{Template:Fortify}}
  
==Abstract==
+
[[Category:FIXME|This is the text from the old template. This needs to be rewritten using the new template.]]
 +
 
 +
Last revision (mm/dd/yy): '''{{REVISIONMONTH}}/{{REVISIONDAY}}/{{REVISIONYEAR}}'''
 +
 
 +
[[ASDR_TOC_Vulnerabilities|Vulnerabilities Table of Contents]]
 +
 
 +
[[ASDR Table of Contents]]
 +
__TOC__
  
Improperly scrubbing sensitive data from memory can compromise security.
 
  
 
==Description==
 
==Description==
 +
 +
Improperly scrubbing sensitive data from memory can compromise security.
  
 
Compiler optimization errors occur when:
 
Compiler optimization errors occur when:
Line 14: Line 22:
 
* The source code is compiled using an optimizing compiler, which identifies and removes the function that overwrites the contents as a dead store because the memory is not used subsequently.  
 
* The source code is compiled using an optimizing compiler, which identifies and removes the function that overwrites the contents as a dead store because the memory is not used subsequently.  
  
==Examples ==
 
  
'''Example: "Dead store removal"'''
+
==Risk Factors==
 +
 
 +
* Talk about the [[OWASP Risk Rating Methodology|factors]] that make this vulnerability likely or unlikely to actually happen
 +
* Discuss the technical impact of a successful exploit of this vulnerability
 +
* Consider the likely [business impacts] of a successful attack
 +
 
 +
 
 +
==Examples==
 +
 
 +
===Example: "Dead store removal"===
  
 
Memory overwriting code is removed by optimizing compiler, which causes sensitive information left in the memory after its usage.  
 
Memory overwriting code is removed by optimizing compiler, which causes sensitive information left in the memory after its usage.  
Line 40: Line 56:
 
Attackers typically exploit this type of vulnerability by using a core dump or runtime mechanism to access the memory used by a particular application and recover the secret information. Once an attacker has access to the secret information, it is relatively straightforward to further exploit the system and possibly compromise other resources with which the application interacts.
 
Attackers typically exploit this type of vulnerability by using a core dump or runtime mechanism to access the memory used by a particular application and recover the secret information. Once an attacker has access to the secret information, it is relatively straightforward to further exploit the system and possibly compromise other resources with which the application interacts.
  
==Related Threats==
 
  
==Related Attacks==
+
==Related [[Attacks]]==
  
==Related Vulnerabilities==
+
* [[Attack 1]]
 +
* [[Attack 2]]
 +
 
 +
 
 +
==Related [[Vulnerabilities]]==
 +
 
 +
* [[Vulnerability 1]]
 +
* [[Vulnerabiltiy 2]]
 +
 
 +
Note: the contents of "Related Problems" sections should be placed here
 +
 
 +
 
 +
==Related [[Controls]]==
 +
 
 +
* [[Control 1]]
 +
* [[Control 2]]
 +
 
 +
Note: contents of "Avoidance and Mitigation" and "Countermeasure" related Sections should be placed here
 +
 
 +
 
 +
==Related [[Technical Impacts]]==
 +
 
 +
* [[Technical Impact 1]]
 +
* [[Technical Impact 2]]
  
==Related Countermeasures==
 
  
 
==References==
 
==References==
  
[1] M. Howard and D. LeBlanc. Writing Secure Code, Second Edition. Microsoft Press, 2003.
+
* [1] M. Howard and D. LeBlanc. Writing Secure Code, Second Edition. Microsoft Press, 2003.
 +
 
 +
[[Category:FIXME|add links
 +
 
 +
In addition, one should classify vulnerability based on the following subcategories: Ex:<nowiki>[[Category:Error Handling Vulnerability]]</nowiki>
 +
 
 +
Availability Vulnerability
 +
 
 +
Authorization Vulnerability
 +
 
 +
Authentication Vulnerability
 +
 
 +
Concurrency Vulnerability
 +
 
 +
Configuration Vulnerability
 +
 
 +
Cryptographic Vulnerability
 +
 
 +
Encoding Vulnerability
 +
 
 +
Error Handling Vulnerability
 +
 
 +
Input Validation Vulnerability
 +
 
 +
Logging and Auditing Vulnerability
 +
 
 +
Session Management Vulnerability]]
 +
 
 +
__NOTOC__
 +
 
  
==Categories==
+
[[Category:OWASP ASDR Project]]
 
[[Category:Environmental Vulnerability]]
 
[[Category:Environmental Vulnerability]]
 
[[Category:C]]
 
[[Category:C]]

Revision as of 08:15, 26 September 2008

This is a Vulnerability. To view all vulnerabilities, please see the Vulnerability Category page.

This article includes content generously donated to OWASP by Fortify.JPG.

Last revision (mm/dd/yy): 09/26/2008

Vulnerabilities Table of Contents

ASDR Table of Contents


Description

Improperly scrubbing sensitive data from memory can compromise security.

Compiler optimization errors occur when:

  • Secret data is stored in memory.
  • The secret data is scrubbed from memory by overwriting its contents.
  • The source code is compiled using an optimizing compiler, which identifies and removes the function that overwrites the contents as a dead store because the memory is not used subsequently.


Risk Factors

  • Talk about the factors that make this vulnerability likely or unlikely to actually happen
  • Discuss the technical impact of a successful exploit of this vulnerability
  • Consider the likely [business impacts] of a successful attack


Examples

Example: "Dead store removal"

Memory overwriting code is removed by optimizing compiler, which causes sensitive information left in the memory after its usage.

The following code reads a password from the user, uses the password to connect to a back-end mainframe and then attempts to scrub the password from memory using memset().

	 void GetData(char *MFAddr) { 
	 char pwd[64];
	 if (GetPasswordFromUser(pwd, sizeof(pwd))) {
	  if (ConnectToMainframe(MFAddr, pwd)) {
			  // Interaction with mainframe
		 }
	   }
	   memset(pwd, 0, sizeof(pwd));
	}

The code in the example will behave correctly if it is executed verbatim, but if the code is compiled using an optimizing compiler, such as Microsoft Visual C++® .NET or GCC 3.x, then the call to memset() will be removed as a dead store because the buffer pwd is not used after its value is overwritten [1]. Because the buffer pwd contains a sensitive value, the application may be vulnerable to attack if the data is left memory resident. If attackers are able to access the correct region of memory, they may use the recovered password to gain control of the system.

It is common practice to overwrite sensitive data manipulated in memory, such as passwords or cryptographic keys, in order to prevent attackers from learning system secrets. However, with the advent of optimizing compilers, programs do not always behave as their source code alone would suggest. In the example, the compiler interprets the call to memset() as dead code because the memory being written to is not subsequently used, despite the fact that there is clearly a security motivation for the operation to occur. The problem here is that many compilers, and in fact many programming languages, do not take this and other security concerns into consideration in their efforts to improve efficiency.

Attackers typically exploit this type of vulnerability by using a core dump or runtime mechanism to access the memory used by a particular application and recover the secret information. Once an attacker has access to the secret information, it is relatively straightforward to further exploit the system and possibly compromise other resources with which the application interacts.


Related Attacks


Related Vulnerabilities

Note: the contents of "Related Problems" sections should be placed here


Related Controls

Note: contents of "Avoidance and Mitigation" and "Countermeasure" related Sections should be placed here


Related Technical Impacts


References

  • [1] M. Howard and D. LeBlanc. Writing Secure Code, Second Edition. Microsoft Press, 2003.