CWE-122 堆缓冲区溢出
Heap-based Buffer Overflow
结构: Simple
Abstraction: Variant
状态: Draft
被利用可能性: High
基本描述
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
相关缺陷
-
cwe_Nature: ChildOf cwe_CWE_ID: 788 cwe_View_ID: 1000 cwe_Ordinal: Primary
-
cwe_Nature: ChildOf cwe_CWE_ID: 788 cwe_View_ID: 699 cwe_Ordinal: Primary
-
cwe_Nature: ChildOf cwe_CWE_ID: 787 cwe_View_ID: 1000
-
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', 'Modify Memory'] | Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. Besides important user data, heap-based overflows can be used to overwrite function pointers that may be living in memory, pointing it to the attacker's code. Even in applications that do not explicitly use function pointers, the run-time will usually leave many in memory. For example, object methods in C++ are generally implemented using function pointers. Even in C programs, there is often a global offset table used by the underlying runtime. |
| ['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
策略:
Pre-design: Use a language or compiler that performs automatic bounds checking.
Architecture and Design
策略:
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Build and Compilation
策略:
Pre-design through Build: Canary style bounds checking, library changes which ensure the validity of chunk data, and other such fixes are possible, but should not be relied upon.
Implementation
策略:
Implement and perform bounds checking on input.
Implementation
策略: Libraries or Frameworks
Do not use dangerous functions such as gets. Look for their safe equivalent, which checks for the boundary.
Operation
策略:
Use OS-level preventative functionality. This is not a complete solution, but it provides some defense in depth.
示例代码
例
While buffer overflow examples can be rather complex, it is possible to have very simple, yet still exploitable, heap-based buffer overflows:
bad C
int main(int argc, char argv) {
buf = (char )malloc(sizeof(char)*BUFSIZE);
strcpy(buf, argv[1]);
}
The buffer is allocated heap memory with a fixed size, but there is no guarantee the string in argv[1] will not exceed this size and cause an overflow.
例
This example applies an encoding procedure to an input string and stores it into a buffer.
bad C
char dst_buf = (char)malloc(4sizeof(char) * MAX_SIZE);
if ( MAX_SIZE die("user string too long, die evil hacker!");
}
dst_index = 0;
for ( i = 0; i
dst_buf[dst_index++] = 'a';
dst_buf[dst_index++] = 'm';
dst_buf[dst_index++] = 'p';
dst_buf[dst_index++] = ';';
}
else if ('
/ encode to < /
}
else dst_buf[dst_index++] = user_supplied_string[i];
}
return dst_buf;文章来源于互联网:scap中文网
- 左青龙
- 微信扫一扫
-
- 右白虎
- 微信扫一扫
-
评论