CWE-14 编译器移除释放缓冲区的代码
Compiler Removal of Code to Clear Buffers
结构: Simple
Abstraction: Variant
状态: Draft
被利用可能性: unkown
基本描述
Sensitive memory is cleared according to the source code, but compiler optimizations leave the memory untouched when it is not read from again, aka "dead store removal."
扩展描述
This compiler optimization error occurs when:
相关缺陷
-
cwe_Nature: ChildOf cwe_CWE_ID: 733 cwe_View_ID: 699 cwe_Ordinal: Primary
-
cwe_Nature: ChildOf cwe_CWE_ID: 733 cwe_View_ID: 1000 cwe_Ordinal: Primary
适用平台
Language: [{'cwe_Name': 'C', 'cwe_Prevalence': 'Undetermined'}, {'cwe_Name': 'C++', 'cwe_Prevalence': 'Undetermined'}]
常见的影响
| 范围 | 影响 | 注释 |
|---|---|---|
| ['Confidentiality', 'Access Control'] | ['Read Memory', 'Bypass Protection Mechanism'] | This weakness will allow data that has not been cleared from memory to be read. If this data contains sensitive password information, then an attacker can read the password and use the information to bypass protection mechanisms. |
检测方法
Black Box
White Box
可能的缓解方案
Implementation
策略:
Store the sensitive data in a "volatile" memory location if available.
Build and Compilation
策略:
If possible, configure your compiler so that it does not remove dead stores.
Architecture and Design
策略:
Where possible, encrypt sensitive data that are used by a software system.
示例代码
例
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().
bad C
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 [18]. Because the buffer pwd contains a sensitive value, the application may be vulnerable to attack if the data are 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.
分类映射
| 映射的分类名 | ImNode ID | Fit | Mapped Node Name |
|---|---|---|---|
| 7 Pernicious Kingdoms | Insecure Compiler Optimization | ||
| PLOVER | Sensitive memory uncleared by compiler optimization | ||
| OWASP Top Ten 2004 | A8 | CWE More Specific | Insecure Storage |
| CERT C Secure Coding | MSC06-C | Be aware of compiler optimization when dealing with sensitive data | |
| Software Fault Patterns | SFP23 | Exposed Data |
引用
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