CWE-125 跨界内存读

admin 2022年1月7日02:53:55CWE(弱点枚举)评论11 views3206字阅读10分41秒阅读模式

CWE-125 跨界内存读

Out-of-bounds Read

结构: Simple

Abstraction: Base

状态: Draft

被利用可能性: unkown

基本描述

The software reads data past the end, or before the beginning, of the intended buffer.

扩展描述

Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.

相关缺陷

  • cwe_Nature: ChildOf cwe_CWE_ID: 119 cwe_View_ID: 1000 cwe_Ordinal: Primary

  • cwe_Nature: ChildOf cwe_CWE_ID: 119 cwe_View_ID: 1003 cwe_Ordinal: Primary

  • cwe_Nature: ChildOf cwe_CWE_ID: 119 cwe_View_ID: 699 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 Read Memory
Confidentiality Bypass Protection Mechanism By reading out-of-bounds memory, an attacker might be able to get secret values, such as memory addresses, which can be bypass protection mechanisms such as ASLR in order to improve the reliability and likelihood of exploiting a separate weakness to achieve code execution instead of just denial of service.

可能的缓解方案

MIT-5 Implementation

策略: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a whitelist of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
Do not rely exclusively on looking for malicious or malformed inputs (i.e., do not rely on a blacklist). A blacklist is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, blacklists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be espcially careful of relying on a sentinel (i.e. special character such as NUL) in an untrusted inputs.

Architecture and Design

策略: Language Selection

Use a language that provides appropriate memory abstractions.

示例代码

In the following code, the method retrieves a value from an array at a specific array index location that is given as an input parameter to the method

bad C

int getValueFromArray(int *array, int len, int index) {


int value;

// check that the array index is less than the maximum

// length of the array

if (index


// get the value at the specified index of the array

value = array[index];

}
// if array index is invalid then output error message

// and return value indicating error

else {

printf("Value is: %dn", array[index]);
value = -1;

}

return value;

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  • 本文由 发表于 2022年1月7日02:53:55
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