CVE-2014-0315

Vulnerability

The vulnerability, identified as CVE-2014-0315, is an untrusted search path vulnerability in Microsoft Windows. It exists in the way Windows processes .bat and .cmd files when they are run from network locations or the current working directory. The affected software includes Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 [1]. Specifically, when a user runs a batch script, the system searches for cmd.exe in the current working directory before checking the system path, allowing a malicious cmd.exe placed in that directory to be executed [2].

Exploitation

An attacker must first convince a user to navigate to a directory containing a crafted .bat or .cmd file and a malicious cmd.exe [1]. The user must then run the batch file. For local exploitation, the attacker needs the ability to place files in the current working directory (e.g., via a previously compromised account or removable media). The attacker does not need network access but requires user interaction. The exploitation sequence involves the victim opening a .bat or .cmd file from a directory that also contains a trojan cmd.exe, which the system loads instead of the legitimate one, executing arbitrary code [2].

Impact

Successful exploitation allows an attacker to execute arbitrary code with the privileges of the current user. If the user has administrative rights, the attacker can gain full control of the system, leading to complete compromise of confidentiality, integrity, and availability [1]. The vulnerability is rated Important by Microsoft [1].

Mitigation

Microsoft released security update MS14-019 on April 8, 2014, to address this vulnerability [1]. The update corrects the way Windows processes .bat and .cmd files from network locations, preventing the untrusted search path behavior. Users with automatic updating enabled received the update automatically. For systems that cannot be updated, no workaround is documented, and the vulnerability is not listed in the Known Exploited Vulnerabilities (KEV) catalog [1].