Title: Alcatel Speed Touch Pro ADSL Insecure Embedded TFTP Server Vulnerability
Severity: CRITICAL
Description:
Certain models of the Alcatel Speed Touch family of ADSL-Ethernet router/bridge products exhibit serious security flaws.
Certain Alcatel ADSL-Ethernet bridge products (Speed Touch Pro) feature an embedded TFTP server which can be used by remote users to make changes to configuration and firmware.
Normally, the TFTP service in such a device would not be accessible from the WAN.
In this case, however, the interface is available to both extranet users and attackers local to the copper loop on which the DSL connection is carried.
By making use of a spoofed UDP "bounce" with a source address set to the IP broadcast address (255.255.255.255) and a source port set to 69 (tftp), tftp connections may be made from the extranet directly to the bridge.
The bridge also listens directly for tftp connections on the Telco/WAN side. As a result, the tftp service is open to properly equipped attackers able to make a connection to the ADSL line (for example, at the home's telephone service "demarc" point, or similar Telco access point).
Since TFTP provides no support for user authentication, this leaves the device's admin interface and firmware upload feature completely open to any attacker.
Moreover, user-supplied firmware code transferred to the router/bridge is not checked for authenticity, and an attacker may exploit the open TFTP interface to install malicious code on the device.
This permit such malicious actions as:
- installation a network sniffer, compromising traffic on the device's network.
- turning the device into a relay for other attacks, such as denials of service (DoS "zombie") and man-in-the-middle attacks.
No method is available for disabling the vulnerable TFTP service.
*** NOTE: Shortly after this advisory was published, the vendor, Alcatel, posted their response to the reported vulnerabilities in their modems.
In addition to providing general mitigating strategies designed to lessen the impact of these isses (such as firewall software and/or a dedicated firewall device or the Alcatel Speed Touch modem with Firewall capabilities), the vendor response indicates that only the Speed Touch Pro is vulnerable to remote changes to firmware code and configuration settings, and that this model can be made secure from such interference by the activation of an inbuilt security feature disabling remote access from the WAN/DSL interface. Therefore, while the discoverer's initial advisory states that the entire family of devices may be vulnerable, the vendor limits the scope of this vulnerability to a single, misconfigured model of the Speed Touch line.
This discussion will be updated regularly as further details and clarification emerge.
Affected Products:
- Alcatel Speed Touch Home 0.0.0 KHDSAA.108
- Alcatel Speed Touch Home 0.0.0 KHDSAA.132
- Alcatel Speed Touch Home 0.0.0 KHDSAA.133
- Alcatel Speed Touch Home 0.0.0 KHDSAA.134
References:
- Alcatel: Alcatel ADSL Modem Security Information
- Alcatel: Alcatel Speed Touch Home Product Information
- Alcatel: Alcatel Speed Touch Pro Product Information
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