CWE-416 释放后使用
Use After Free
结构: Simple
Abstraction: Variant
状态: Stable
被利用可能性: High
基本描述
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
扩展描述
The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system's reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:
In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process.
If the newly allocated data chances to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
相关缺陷
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cwe_Nature: ChildOf cwe_CWE_ID: 825 cwe_View_ID: 1000 cwe_Ordinal: Primary
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cwe_Nature: ChildOf cwe_CWE_ID: 672 cwe_View_ID: 1003 cwe_Ordinal: Primary
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cwe_Nature: CanPrecede cwe_CWE_ID: 120 cwe_View_ID: 1000
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cwe_Nature: CanPrecede cwe_CWE_ID: 123 cwe_View_ID: 1000
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 |
|---|---|---|
| Integrity | Modify Memory | The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere. |
| Availability | DoS: Crash, Exit, or Restart | If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information. |
| ['Integrity', 'Confidentiality', 'Availability'] | Execute Unauthorized Code or Commands | If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. |
可能的缓解方案
Architecture and Design
策略:
Choose a language that provides automatic memory management.
Implementation
策略:
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
示例代码
例
The following example demonstrates the weakness.
bad C
#include
#define BUFSIZER1 512
#define BUFSIZER2 ((BUFSIZER1/2) - 8)
int main(int argc, char argv) {
char buf2R1;
char buf2R2;
char buf3R2;
buf1R1 = (char ) malloc(BUFSIZER1);
buf2R1 = (char ) malloc(BUFSIZER1);
free(buf2R1);
buf2R2 = (char ) malloc(BUFSIZER2);
buf3R2 = (char ) malloc(BUFSIZER2);
strncpy(buf2R1, argv[1], BUFSIZER1-1);
free(buf1R1);
free(buf2R2);
free(buf3R2);
}
例
The following code illustrates a use after free error:
bad C
if (err) {
free(ptr);
}
...
if (abrt) {
}
When an error occurs, the pointer is immediately freed. However, this pointer is later incorrectly used in the logError function.
分析过的案例
| 标识 | 说明 | 链接 |
|---|---|---|
| CVE-2010-4168 | Use-after-free triggered by closing a connection while data is still being transmitted. | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-4168 |
| CVE-2010-2941 | Improper allocation for invalid data leads to use-after-free. | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2941 |
| CVE-2010-2547 | certificate with a large number of Subject Alternate Names not properly handled in realloc, leading to use-after-free | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2547 |
| CVE-2010-1772 | Timers are not disabled when a related object is deleted | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-1772 |
| CVE-2010-1437 | Access to a "dead" object that is being cleaned up | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-1437 |
| CVE-2010-1208 | object is deleted even with a non-zero reference count, and later accessed | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-1208 |
| CVE-2010-0629 | use-after-free involving request containing an invalid version number | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-0629 |
| CVE-2010-0378 | unload of an object that is currently being accessed by other functionality | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-0378 |
| CVE-2010-0302 | incorrectly tracking a reference count leads to use-after-free | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-0302 |
| CVE-2010-0249 | use-after-free related to use of uninitialized memory | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-0249 |
| CVE-2010-0050 | HTML document with incorrectly-nested tags | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-0050 |
| CVE-2009-3658 | Use after free in ActiveX object by providing a malformed argument to a method | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-3658 |
| CVE-2009-3616 | use-after-free by disconnecting during data transfer, or a message containing incorrect data types | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-3616 |
| CVE-2009-3553 | disconnect during a large data transfer causes incorrect reference count, leading to use-after-free | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-3553 |
| CVE-2009-2416 | use-after-free found by fuzzing | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-2416 |
| CVE-2009-1837 | Chain: race condition (CWE-362) from improper handling of a page transition in web client while an applet is loading (CWE-368) leads to use after free (CWE-416) | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1837 |
| CVE-2009-0749 | realloc generates new buffer and pointer, but previous pointer is still retained, leading to use after free | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-0749 |
| CVE-2010-3328 | Use-after-free in web browser, probably resultant from not initializing memory. | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-3328 |
| CVE-2008-5038 | use-after-free when one thread accessed memory that was freed by another thread | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-5038 |
| CVE-2008-0077 | assignment of malformed values to certain properties triggers use after free | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0077 |
| CVE-2006-4434 | mail server does not properly handle a long header. | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4434 |
| CVE-2010-2753 | chain: integer overflow leads to use-after-free | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2753 |
| CVE-2006-4997 | freed pointer dereference | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4997 |
分类映射
| 映射的分类名 | ImNode ID | Fit | Mapped Node Name |
|---|---|---|---|
| 7 Pernicious Kingdoms | Use After Free | ||
| CLASP | Using freed memory | ||
| CERT C Secure Coding | MEM00-C | Allocate and free memory in the same module, at the same level of abstraction | |
| CERT C Secure Coding | MEM01-C | Store a new value in pointers immediately after free() | |
| CERT C Secure Coding | MEM30-C | Exact | Do not access freed memory |
| Software Fault Patterns | SFP15 | Faulty Resource Use |
引用
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