CWE-121 栈缓冲区溢出
Stack-based Buffer Overflow
结构: Simple
Abstraction: Variant
状态: Draft
被利用可能性: High
基本描述
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
相关缺陷
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cwe_Nature: ChildOf cwe_CWE_ID: 788 cwe_View_ID: 1000 cwe_Ordinal: Primary
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cwe_Nature: ChildOf cwe_CWE_ID: 788 cwe_View_ID: 699 cwe_Ordinal: Primary
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cwe_Nature: ChildOf cwe_CWE_ID: 787 cwe_View_ID: 1000
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cwe_Nature: ChildOf cwe_CWE_ID: 787 cwe_View_ID: 699
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 |
|---|---|---|
| Availability | ['DoS: Crash, Exit, or Restart', 'DoS: Resource Consumption (CPU)', 'DoS: Resource Consumption (Memory)'] | Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop. |
| ['Integrity', 'Confidentiality', 'Availability', 'Access Control'] | ['Execute Unauthorized Code or Commands', 'Bypass Protection Mechanism'] | Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. |
| ['Integrity', 'Confidentiality', 'Availability', 'Access Control', 'Other'] | ['Execute Unauthorized Code or Commands', 'Bypass Protection Mechanism', 'Other'] | When the consequence is arbitrary code execution, this can often be used to subvert any other security service. |
可能的缓解方案
MIT-10 Build and Compilation
策略: Compilation or Build Hardening
Run or compile the software using features or extensions that automatically provide a protection mechanism that mitigates or eliminates buffer overflows.
For example, certain compilers and extensions provide automatic buffer overflow detection mechanisms that are built into the compiled code. Examples include the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice.
Architecture and Design
策略:
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Build and Compilation
策略:
Compiler-based canary mechanisms such as StackGuard, ProPolice and the Microsoft Visual Studio /GS flag. Unless this provides automatic bounds checking, it is not a complete solution.
Implementation
策略:
Implement and perform bounds checking on input.
Implementation
策略:
Do not use dangerous functions such as gets. Use safer, equivalent functions which check for boundary errors.
Operation
策略:
Use OS-level preventative functionality, such as ASLR. This is not a complete solution.
示例代码
例
While buffer overflow examples can be rather complex, it is possible to have very simple, yet still exploitable, stack-based buffer overflows:
bad C
int main(int argc, char **argv) {
strcpy(buf, argv[1]);
}
The buffer size is fixed, but there is no guarantee the string in argv[1] will not exceed this size and cause an overflow.
例
This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer.
bad C
in_addr_t addr;
char hostname[64];
in_addr_t inet_addr(const char cp);
/routine that ensures user_supplied_addr is in the right format for conversion /
validate_addr_form(user_supplied_addr);
addr = inet_addr(user_supplied_addr);
hp = gethostbyaddr( addr, sizeof(struct in_addr), AF_INET);
strcpy(hostname, hp->h_name);
}
This function allocates a buffer of 64 bytes to store the hostname, however there is no guarantee that the hostname will not be larger than 64 bytes. If an attacker specifies an address which resolves to a very large hostname, then we may overwrite sensitive data or even relinquish control flow to the attacker.
Note that this example also contains an unchecked return value (CWE-252) that can lead to a NULL pointer dereference (CWE-476).
Notes
分类映射
| 映射的分类名 | ImNode ID | Fit | Mapped Node Name |
|---|---|---|---|
| CLASP | Stack overflow | ||
| Software Fault Patterns | SFP8 | Faulty Buffer Access | |
| CERT C Secure Coding | ARR38-C | Imprecise | Guarantee that library functions do not form invalid pointers |
| CERT C Secure Coding | STR31-C | CWE More Specific | Guarantee that storage for strings has sufficient space for character data and the null terminator |
引用
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