logo

Missing Initialization of Resource

Incomplete Class
Structure: Simple
Description

The software fails to properly set up a critical resource before using it.

Extended Description

Many system resources, like memory buffers, file handles, or configuration objects, need explicit setup before they're safe to use. When this initialization step is skipped, the resource may contain leftover data from previous operations, expired values, or system defaults that are invalid for your specific use case. This unpredictable state becomes a security problem when your code assumes the resource has specific, trustworthy properties. From a developer's perspective, this often happens when you allocate a resource but don't populate it with known, safe values. Attackers can exploit this by manipulating or predicting the uninitialized content, leading to information leaks, crashes, or unexpected program behavior. Always explicitly initialize all resources to a known, secure state, even if you think the system or compiler will do it for you.
Common Consequences 2
Scope: Confidentiality

Impact: Read MemoryRead 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.

Scope: Availability

Impact: DoS: Crash, Exit, or Restart

The uninitialized resource may contain values that cause program flow to change in ways that the programmer did not intend.
Potential Mitigations 4
Phase: Implementation
Explicitly initialize the resource before use. If this is performed through an API function or standard procedure, follow all specified steps.
Phase: Implementation
Pay close attention to complex conditionals that affect initialization, since some branches might not perform the initialization.
Phase: Implementation
Avoid race conditions (Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')) during initialization routines.
Phase: Build and Compilation
Run or compile your product with settings that generate warnings about uninitialized variables or data.
Demonstrative Examples 4

ID : DX-105

Here, a boolean initiailized field is consulted to ensure that initialization tasks are only completed once. However, the field is mistakenly set to true during static initialization, so the initialization code is never reached.

Code Example:

Bad
Java
java

// perform initialization tasks* ...

java

ID : DX-54

The following code intends to limit certain operations to the administrator only.

Code Example:

Bad
Perl
perl

do stuff*

perl
If the application is unable to extract the state information - say, due to a database timeout - then the $uid variable will not be explicitly set by the programmer. This will cause $uid to be regarded as equivalent to "0" in the conditional, allowing the original user to perform administrator actions. Even if the attacker cannot directly influence the state data, unexpected errors could cause incorrect privileges to be assigned to a user just by accident.
The following code intends to concatenate a string to a variable and print the string.
Code Example:
Bad
C
c
This might seem innocent enough, but str was not initialized, so it contains random memory. As a result, str[0] might not contain the null terminator, so the copy might start at an offset other than 0. The consequences can vary, depending on the underlying memory.
If a null terminator is found before str[8], then some bytes of random garbage will be printed before the "hello world" string. The memory might contain sensitive information from previous uses, such as a password (which might occur as a result of Compiler Removal of Code to Clear Buffers or Improper Clearing of Heap Memory Before Release ('Heap Inspection')). In this example, it might not be a big deal, but consider what could happen if large amounts of memory are printed out before the null terminator is found.
If a null terminator isn't found before str[8], then a buffer overflow could occur, since strcat will first look for the null terminator, then copy 12 bytes starting with that location. Alternately, a buffer over-read might occur (Buffer Over-read) if a null terminator isn't found before the end of the memory segment is reached, leading to a segmentation fault and crash.
ID : DX-144
This example will leave test_string in an unknown condition when i is the same value as err_val, because test_string is not initialized (Missing Initialization of a Variable). Depending on where this code segment appears (e.g. within a function body), test_string might be random if it is stored on the heap or stack. If the variable is declared in static memory, it might be zero or NULL. Compiler optimization might contribute to the unpredictability of this address.
Code Example:
Bad
C
char *test_string;
if (i != err_val)
{


c
When the printf() is reached, test_string might be an unexpected address, so the printf might print junk strings (Use of Uninitialized Variable).


 To fix this code, there are a couple approaches to making sure that test_string has been properly set once it reaches the printf().


One solution would be to set test_string to an acceptable default before the conditional:
Code Example:
Good
C
char *test_string = "Done at the beginning";
if (i != err_val)
{


c
Another solution is to ensure that each branch of the conditional - including the default/else branch - could ensure that test_string is set:
Code Example:
Good
C
char *test_string;
if (i != err_val)
{


c
  
Observed Examples 2
CVE-2020-20739A variable that has its value set in a conditional statement is sometimes used when the conditional fails, sometimes causing data leakage
CVE-2005-1036Chain: Bypass of access restrictions due to improper authorization (Missing Authorization) of a user results from an improperly initialized (Missing Initialization of Resource) I/O permission bitmap
   
  
  
 
 
Likelihood of Exploit 
 
 
 
 Medium 
 
 
  
 
 
Applicable Platforms 
 
 
 
 
 
Languages:
 
 
 Not Language-Specific : Undetermined 
  
  
 
 
 
  
 
 
Modes of Introduction 
 
 
 
 
 
  Implementation  
 
 
 
          
 
 
Related Weaknesses 
 
 
 
 
  ChildOf:
 Improper Initialization (CWE-665) 
  ChildOf:
 Improper Initialization (CWE-665) 
  CanPrecede:
 Use of Uninitialized Resource (CWE-908)