CVE-2016-0754 in cURL
Summary
by MITRE
cURL before 7.47.0 on Windows allows attackers to write to arbitrary files in the current working directory on a different drive via a colon in a remote file name.
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Analysis
by VulDB Data Team • 07/11/2018
The vulnerability identified as CVE-2016-0754 represents a critical file system manipulation issue within the cURL library version 7.47.0 and earlier on Windows operating systems. This flaw stems from insufficient input validation when processing remote file names that contain colon characters, creating a path traversal condition that allows malicious actors to write files to arbitrary locations on different drives within the system. The vulnerability specifically affects Windows implementations where cURL processes remote file names without proper sanitization of special characters that could alter the intended file path.
The technical implementation of this vulnerability exploits the way Windows handles file paths when a colon character appears within a remote file name. In Windows file systems, colons are typically used to separate drive letters from file paths, such as in c:file.txt format. When cURL processes a remote file name containing a colon, it fails to properly parse the path structure, leading to a situation where the application interprets the portion before the colon as a drive letter and the portion after as a file path. This misinterpretation allows attackers to specify absolute paths on different drives, bypassing normal file system restrictions and potentially writing malicious content to system directories or other critical locations.
The operational impact of this vulnerability extends beyond simple file system manipulation to encompass potential privilege escalation and system compromise scenarios. An attacker could leverage this flaw to write executable files to system directories, potentially enabling code execution or persistence mechanisms. The vulnerability particularly affects environments where cURL is used to download files from untrusted sources, such as web applications that utilize cURL for file retrieval operations. The current working directory context means that even if the remote file name is properly formatted, the colon character could still trigger the vulnerability if the application does not properly validate the remote file name before processing.
This vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The flaw demonstrates a classic example of insufficient input validation where the application fails to properly sanitize user-supplied data before using it in file system operations. From an adversary perspective, this vulnerability maps to ATT&CK technique T1059.007 for command and scripting interpreter, as it could enable attackers to place malicious executables in system directories or create scripts that execute with elevated privileges. The attack surface is particularly concerning in web applications that utilize cURL for file downloads, as these applications may be vulnerable to remote exploitation when processing user-provided file names from external sources.
Mitigation strategies for CVE-2016-0754 should focus on immediate version updates to cURL 7.47.0 or later, which contain the necessary patches to properly sanitize file names containing special characters. Organizations should implement strict input validation measures for any file name processing, particularly in applications that interface with external file systems or web services. Network segmentation and access controls should be implemented to limit the potential impact of successful exploitation, while regular security audits should verify that applications properly validate file system operations. Additionally, system administrators should monitor for unusual file creation patterns in system directories, as these could indicate exploitation attempts. The vulnerability underscores the importance of proper input validation and path handling in network applications, particularly when dealing with cross-platform compatibility issues where different operating systems may interpret file paths differently.