CVE-2010-0039 in Time Capsule
Summary
by MITRE
The Application-Level Gateway (ALG) on the Apple Time Capsule, AirPort Extreme Base Station, and AirPort Express Base Station with firmware before 7.5.2 modifies PORT commands in incoming FTP traffic, which allows remote attackers to use the device s IP address for arbitrary intranet TCP traffic by leveraging write access to an intranet FTP server.
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Analysis
by VulDB Data Team • 10/07/2021
The vulnerability identified as CVE-2010-0039 affects Apple Time Capsule, AirPort Extreme Base Station, and AirPort Express Base Station devices running firmware versions prior to 7.5.2. This issue resides within the Application-Level Gateway component that processes FTP traffic, specifically targeting how the system handles PORT commands in incoming FTP sessions. The ALG functionality is designed to facilitate proper NAT traversal for FTP connections by translating IP addresses and port numbers, but this implementation contains a critical flaw that enables attackers to manipulate network traffic in unintended ways.
The technical flaw manifests when the ALG component processes FTP PORT commands from external sources. Normally, FTP uses two connections - a control connection and a data connection - where the PORT command specifies the IP address and port number for the data connection. In affected Apple devices, the ALG incorrectly modifies these PORT commands, allowing remote attackers to inject malicious IP addresses into the data connection parameters. This modification enables attackers with write access to an intranet FTP server to redirect TCP traffic through the wireless access point, effectively using the device's own IP address as a gateway for arbitrary intranet communications.
The operational impact of this vulnerability represents a significant security risk for organizations using affected Apple networking equipment. Attackers can leverage this flaw to bypass network segmentation controls and gain unauthorized access to internal network resources that would normally be protected by firewall rules. The vulnerability essentially creates a backdoor path through the network infrastructure, allowing malicious actors to establish connections to internal systems that should only be accessible through the internal network. This type of attack aligns with techniques described in the ATT&CK framework under network infiltration and lateral movement tactics, where adversaries exploit network device vulnerabilities to expand their access within a compromised network.
The vulnerability maps to CWE-129, which describes improper validation of input boundaries, and CWE-20, which covers input validation issues. The flaw specifically involves improper handling of network protocol parameters that should be validated before being processed. Organizations should implement immediate mitigations including firmware updates to version 7.5.2 or later, which addresses the ALG modification behavior. Network segmentation strategies should be reviewed to limit the impact of potential exploitation, and monitoring should be enhanced to detect anomalous FTP traffic patterns. Additionally, administrators should consider disabling FTP ALG functionality if it is not strictly required, as this would eliminate the attack vector entirely. The vulnerability demonstrates the importance of proper input validation in network security devices and highlights the critical need for regular firmware updates to address known security flaws in networking infrastructure equipment.