Description

The software does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

This can have security implications when the associated resource is expected to have certain properties or values, such as a variable that determines whether a user has been authenticated or not.

Modes of Introduction:

– Implementation

 

Likelihood of Exploit: Medium

 

Related Weaknesses

CWE-664

 

Consequences

Confidentiality: Read Memory, Read Application Data

When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.

Access Control: Bypass Protection Mechanism

If security-critical decisions rely on a variable having a “0” or equivalent value, and the programming language performs this initialization on behalf of the programmer, then a bypass of security may occur.

Availability: DoS: Crash, Exit, or Restart

The uninitialized data may contain values that cause program flow to change in ways that the programmer did not intend. For example, if an uninitialized variable is used as an array index in C, then its previous contents may produce an index that is outside the range of the array, possibly causing a crash or an exit in other environments.

 

Potential Mitigations

Phase: Requirements

Description: 

Phase: Architecture and Design

Description: 

Identify all variables and data stores that receive information from external sources, and apply input validation to make sure that they are only initialized to expected values.

Phase: Implementation

Description: 

Explicitly initialize all your variables and other data stores, either during declaration or just before the first usage.

Phase: Implementation

Description: 

Pay close attention to complex conditionals that affect initialization, since some conditions might not perform the initialization.

Phase: Implementation

Description: 

Avoid race conditions (CWE-362) during initialization routines.

Phase: Build and Compilation

Description: 

Run or compile your software with settings that generate warnings about uninitialized variables or data.

Phase: Testing

Description: 

Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.

CVE References

• CVE-2001-1471
  • chain: an invalid value prevents a library file from being included, skipping initialization of key variables, leading to resultant eval injection.

• CVE-2008-3637
  • Improper error checking in protection mechanism produces an uninitialized variable, allowing security bypass and code execution.

• CVE-2008-4197
  • Use of uninitialized memory may allow code execution.

• CVE-2008-2934
  • Free of an uninitialized pointer leads to crash and possible code execution.

• CVE-2007-3749
  • OS kernel does not reset a port when starting a setuid program, allowing local users to access the port and gain privileges.

• CVE-2008-0063
  • Product does not clear memory contents when generating an error message, leading to information leak.

• CVE-2008-0062
  • Lack of initialization triggers NULL pointer dereference or double-free.

• CVE-2008-0081
  • Uninitialized variable leads to code execution in popular desktop application.

• CVE-2008-3688
  • chain: Uninitialized variable leads to infinite loop.

• CVE-2008-3475
  • chain: Improper initialization leads to memory corruption.

• CVE-2008-5021
  • Composite: race condition allows attacker to modify an object while it is still being initialized, causing software to access uninitialized memory.

• CVE-2005-1036
  • Chain: Bypass of access restrictions due to improper authorization (CWE-862) of a user results from an improperly initialized (CWE-909) I/O permission bitmap

• CVE-2008-3597
  • chain: game server can access player data structures before initialization has happened leading to NULL dereference

• CVE-2009-2692
  • chain: uninitialized function pointers can be dereferenced allowing code execution

• CVE-2009-0949
  • chain: improper initialization of memory can lead to NULL dereference

• CVE-2009-3620
  • chain: some unprivileged ioctls do not verify that a structure has been initialized before invocation, leading to NULL dereference