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Class · High

CWE-665: Improper Initialization

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

CWE-665 · Class Level ·16 CVEs ·6 Mitigations

Description

The product 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.

Potential Impact

Confidentiality

Read Memory, Read Application Data

Access Control

Bypass Protection Mechanism

Availability

DoS: Crash, Exit, or Restart

Demonstrative Examples

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.
Bad
private boolean initialized = true;public void someMethod() {
                        if (!initialized) {
                              
                                 
                                 // perform initialization tasks
                                 ...
                                 initialized = true;
                           }
The following code intends to limit certain operations to the administrator only.
Bad
$username = GetCurrentUser();$state = GetStateData($username);if (defined($state)) {$uid = ExtractUserID($state);}
                     
                     # do stuff
                     if ($uid == 0) {DoAdminThings();}
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.
Bad
char str[20];strcat(str, "hello world");printf("%s", str);
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 CWE-14 or CWE-244). 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 (CWE-126) if a null terminator isn't found before the end of the memory segment is reached, leading to a segmentation fault and crash.

Mitigations & Prevention

Requirements

Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable's type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interp

Architecture and Design

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.

Implementation

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

Implementation

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

Implementation

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

Build and Compilation

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

Detection Methods

  • Automated Dynamic Analysis Moderate — This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash
  • Manual Dynamic Analysis — Identify error conditions that are not likely to occur during normal usage and trigger them. For example, run the program under low memory conditions, run with insufficient privileges or permissions, interrupt a transaction before it is completed, or disable connectivity to basic network services su
  • Automated Static Analysis High — Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then sea

Real-World CVE Examples

CVE IDDescription
CVE-2001-1471chain: an invalid value prevents a library file from being included, skipping initialization of key variables, leading to resultant eval injection.
CVE-2008-3637Improper error checking in protection mechanism produces an uninitialized variable, allowing security bypass and code execution.
CVE-2008-4197Use of uninitialized memory may allow code execution.
CVE-2008-2934Free of an uninitialized pointer leads to crash and possible code execution.
CVE-2007-3749OS kernel does not reset a port when starting a setuid program, allowing local users to access the port and gain privileges.
CVE-2008-0063Product does not clear memory contents when generating an error message, leading to information leak.
CVE-2008-0062Lack of initialization triggers NULL pointer dereference or double-free.
CVE-2008-0081Uninitialized variable leads to code execution in popular desktop application.
CVE-2008-3688chain: Uninitialized variable leads to infinite loop.
CVE-2008-3475chain: Improper initialization leads to memory corruption.
CVE-2008-5021Composite: race condition allows attacker to modify an object while it is still being initialized, causing software to access uninitialized memory.
CVE-2005-1036Chain: 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-2008-3597chain: game server can access player data structures before initialization has happened leading to NULL dereference
CVE-2009-2692Chain: Use of an unimplemented network socket operation pointing to an uninitialized handler function (CWE-456) causes a crash because of a null pointer dereference (CWE-476)
CVE-2009-0949chain: improper initialization of memory can lead to NULL dereference

Showing 15 of 16 observed examples.

CWE-664: Improper Control of a Resource Through its Lifetime

The product does not maintain or incorrectly maintains control over a resource throughout its lifetime of creation, use,...

Taxonomy Mappings

  • PLOVER: — Incorrect initialization
  • CERT C Secure Coding: ARR02-C — Explicitly specify array bounds, even if implicitly defined by an initializer
  • The CERT Oracle Secure Coding Standard for Java (2011): DCL00-J — Prevent class initialization cycles
  • Software Fault Patterns: SFP4 — Unchecked Status Condition

Frequently Asked Questions

What is CWE-665?

CWE-665 (Improper Initialization) is a software weakness identified by MITRE's Common Weakness Enumeration. It is classified as a Class-level weakness. The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

How can CWE-665 be exploited?

Attackers can exploit CWE-665 (Improper Initialization) to read memory, read application data. This weakness is typically introduced during the Implementation, Operation phase of software development.

How do I prevent CWE-665?

Key mitigations include: Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, in Java, if the programmer does not explicitl

What is the severity of CWE-665?

CWE-665 is classified as a Class-level weakness (High abstraction). It has been observed in 16 real-world CVEs.