CWE-404 不恰当的资源关闭或释放

Improper Resource Shutdown or Release

结构: Simple

Abstraction: Class

状态: Draft

被利用可能性: Medium

基本描述

The program does not release or incorrectly releases a resource before it is made available for re-use.

扩展描述

When a resource is created or allocated, the developer is responsible for properly releasing the resource as well as accounting for all potential paths of expiration or invalidation, such as a set period of time or revocation.

相关缺陷

  • cwe_Nature: ChildOf cwe_CWE_ID: 664 cwe_View_ID: 1000 cwe_Ordinal: Primary

  • cwe_Nature: PeerOf cwe_CWE_ID: 405 cwe_View_ID: 1000

  • cwe_Nature: CanPrecede cwe_CWE_ID: 619 cwe_View_ID: 1000

  • cwe_Nature: CanPrecede cwe_CWE_ID: 619 cwe_View_ID: 699

适用平台

Language: {'cwe_Class': 'Language-Independent', 'cwe_Prevalence': 'Undetermined'}

常见的影响

范围 影响 注释
['Availability', 'Other'] ['DoS: Resource Consumption (Other)', 'Varies by Context'] Most unreleased resource issues result in general software reliability problems, but if an attacker can intentionally trigger a resource leak, the attacker might be able to launch a denial of service attack by depleting the resource pool.
Confidentiality Read Application Data When a resource containing sensitive information is not correctly shutdown, it may expose the sensitive data in a subsequent allocation.

检测方法

DM-2 Automated Dynamic Analysis

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, or generate incorrect results.

Resource clean up errors might be detected with a stress-test by calling the software simultaneously from a large number of threads or processes, and look for evidence of any unexpected behavior. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

DM-12 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 such as DNS. Monitor the software for any unexpected behavior. If you trigger an unhandled exception or similar error that was discovered and handled by the application's environment, it may still indicate unexpected conditions that were not handled by the application itself.

可能的缓解方案

MIT-3 Requirements

策略: Language Selection

Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, languages such as Java, Ruby, and Lisp perform automatic garbage collection that releases memory for objects that have been deallocated.

Implementation

策略:

It is good practice to be responsible for freeing all resources you allocate and to be consistent with how and where you free memory in a function. If you allocate memory that you intend to free upon completion of the function, you must be sure to free the memory at all exit points for that function including error conditions.

Implementation

策略:

Memory should be allocated/freed using matching functions such as malloc/free, new/delete, and new[]/delete[].

Implementation

策略:

When releasing a complex object or structure, ensure that you properly dispose of all of its member components, not just the object itself.

示例代码

例

The following method never closes the file handle it opens. The Finalize() method for StreamReader eventually calls Close(), but there is no guarantee as to how long it will take before the Finalize() method is invoked. In fact, there is no guarantee that Finalize() will ever be invoked. In a busy environment, this can result in the VM using up all of its available file handles.

bad Java

private void processFile(string fName) {
StreamWriter sw = new StreamWriter(fName);
string line;
while ((line = sr.ReadLine()) != null){
processLine(line);
}
}

例

This code attempts to open a connection to a database and catches any exceptions that may occur.

bad Java

try {
Connection con = DriverManager.getConnection(some_connection_string);
}
catch ( Exception e ) {
log( e );
}

If an exception occurs after establishing the database connection and before the same connection closes, the pool of database connections may become exhausted. If the number of available connections is exceeded, other users cannot access this resource, effectively denying access to the application.

例

Under normal conditions the following C# code executes a database query, processes the results returned by the database, and closes the allocated SqlConnection object. But if an exception occurs while executing the SQL or processing the results, the SqlConnection object is not closed. If this happens often enough, the database will run out of available cursors and not be able to execute any more SQL queries.

bad C#

...
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(queryString);
cmd.Connection = conn;
conn.Open();
SqlDataReader rdr = cmd.ExecuteReader();
HarvestResults(rdr);
conn.Connection.Close();
...

例

The following C function does not close the file handle it opens if an error occurs. If the process is long-lived, the process can run out of file handles.

bad C

int decodeFile(char fName) {
char buf[BUF_SZ];
FILE f = fopen(fName, "r");
if (!f) {
printf("cannot open %s\n", fName);
return DECODE_FAIL;
}
else {
while (fgets(buf, BUF_SZ, f)) {
if (!checkChecksum(buf)) {
return DECODE_FAIL;
}
else {
decodeBlock(buf);
}
}
}
fclose(f);
return DECODE_SUCCESS;
}

例

In this example, the program does not use matching functions such as malloc/free, new/delete, and new[]/delete[] to allocate/deallocate the resource.

bad C++

class A {
void foo();
};
void A::foo(){
int ptr;
ptr = (int)malloc(sizeof(int));
delete ptr;
}

例

In this example, the program calls the delete[] function on non-heap memory.

bad C++

class A{
void foo(bool);
};
void A::foo(bool heap) {
int localArray[2] = {
11,22
};
int *p = localArray;
if (heap){
p = new int[2];
}
delete[] p;
}

分析过的案例

标识 说明 链接
CVE-1999-1127 Does not shut down named pipe connections if malformed data is sent. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-1999-1127
CVE-2001-0830 Sockets not properly closed when attacker repeatedly connects and disconnects from server. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2001-0830
CVE-2002-1372 Return values of file/socket operations not checked, allowing resultant consumption of file descriptors. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2002-1372

Notes

分类映射

映射的分类名 ImNode ID Fit Mapped Node Name
PLOVER Improper resource shutdown or release
7 Pernicious Kingdoms Unreleased Resource
OWASP Top Ten 2004 A9 CWE More Specific Denial of Service
CERT C Secure Coding FIO42-C CWE More Abstract Close files when they are no longer needed
CERT C Secure Coding MEM31-C CWE More Abstract Free dynamically allocated memory when no longer needed
The CERT Oracle Secure Coding Standard for Java (2011) FIO04-J Release resources when they are no longer needed
Software Fault Patterns SFP14 Failure to release resource

相关攻击模式

  • CAPEC-125
  • CAPEC-130
  • CAPEC-131
  • CAPEC-494
  • CAPEC-495
  • CAPEC-496

引用