CVE-2004-1317

Vulnerability

Netcat for Windows version 1.1 contains a stack-based buffer overflow in the doexec.c file. The vulnerability resides in the DNS command parsing routine, where a missing boundary check allows a client command longer than 256 bytes to overwrite the stack [1][2]. Specifically, the code in doexec.c (line 445) did not verify that BufferCnt had not exceeded the receive buffer size, leading to an uncontrolled write when the -e option is active [3]. This issue affects only the Windows port; Unix versions of Netcat are not vulnerable [3].

Exploitation

An attacker can exploit this vulnerability by sending a specially crafted DNS command that exceeds 256 bytes to a Netcat instance running with the -e option (which executes a program and pipes network I/O to its stdio) [1][2]. The attacker requires network connectivity to the target system and no prior authentication, as the overflow occurs during input processing before any authentication check [1]. The exploit can be delivered remotely without user interaction, making it trivially accessible from any network-accessible host [2].

Impact

Successful exploitation allows a remote attacker to execute arbitrary code with the privileges of the Netcat process [1][3]. Because Netcat typically runs with the same privileges as the launching user, this can lead to full system compromise if the user has administrative rights, including data disclosure, modification, and denial of service through arbitrary command execution [1][2].

Mitigation

The vulnerability was fixed in Netcat for Windows version 1.11, released on December 27, 2004 [3][4]. The fix adds a boundary check after reading data into the receive buffer, ensuring the buffer is flushed before an overflow occurs [3]. Users should upgrade to version 1.11 or later, available from www.vulnwatch.org/netcat/ [3][4]. No other mitigations are necessary as the fixed version addresses the root cause.