CWE-243 未改变工作目录时创建chroot Jail
Creation of chroot Jail Without Changing Working Directory
结构: Simple
Abstraction: Variant
状态: Draft
被利用可能性: High
基本描述
The program uses the chroot() system call to create a jail, but does not change the working directory afterward. This does not prevent access to files outside of the jail.
扩展描述
Improper use of chroot() may allow attackers to escape from the chroot jail. The chroot() function call does not change the process's current working directory, so relative paths may still refer to file system resources outside of the chroot jail after chroot() has been called.
相关缺陷
-
cwe_Nature: ChildOf cwe_CWE_ID: 669 cwe_View_ID: 1000 cwe_Ordinal: Primary
适用平台
Language: [{'cwe_Name': 'C', 'cwe_Prevalence': 'Undetermined'}, {'cwe_Name': 'C++', 'cwe_Prevalence': 'Undetermined'}]
Operating_System: {'cwe_Class': 'Unix', 'cwe_Prevalence': 'Undetermined'}
常见的影响
| 范围 | 影响 | 注释 |
|---|---|---|
| Confidentiality | Read Files or Directories |
示例代码
例
Consider the following source code from a (hypothetical) FTP server:
bad C
...
fgets(filename, sizeof(filename), network);
localfile = fopen(filename, "r");
while ((len = fread(buf, 1, sizeof(buf), localfile)) != EOF) {
}
fclose(localfile);
This code is responsible for reading a filename from the network, opening the corresponding file on the local machine, and sending the contents over the network. This code could be used to implement the FTP GET command. The FTP server calls chroot() in its initialization routines in an attempt to prevent access to files outside of /var/ftproot. But because the server does not change the current working directory by calling chdir("/"), an attacker could request the file "../../../../../etc/passwd" and obtain a copy of the system password file.
分类映射
| 映射的分类名 | ImNode ID | Fit | Mapped Node Name |
|---|---|---|---|
| 7 Pernicious Kingdoms | Directory Restriction | ||
| Software Fault Patterns | SFP17 | Failed chroot jail |
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