Title: Ascend SNMP TFTP Attack
Severity: HIGH
Description:
Ascend routers are manageable by the SNMP protocol.
Ascend's SNMP support includes the ability to read and write MIB variables. Ascend's SNMP system is protected by the SNMP community definitions, which act as passwords for SNMP access.
By default, the SNMP 'read' password is "public", and the SNMP 'write' password is "write". An attacker that can guess the SNMP 'read' community can read arbitrary MIB variables, and an attacker that can guess the 'write' community can set arbitrary MIB variables to new values.
Ascend provides a vendor-specific extension MIB. This MIB includes variables that are specific to Ascend equipment.
Among these variables is a group of settings called "sysConfigTftp" that allow the configuration of the router to be manipulated via the TFTP protocol. By writing to these variables with SNMP 'set' messages, an attacker can download the entire configuration of the Ascend router.
The full configuration of an Ascend router includes the telnet password (knowledge of which allows an attacker to gain telnet access to the Ascend menu interface), all the enhanced access passwords (allowing an attacker to reconfigure the router from the menu interface), network protocol authentication keys (including RADIUS and OSPF keys), usernames and passwords for incoming connections, and usernames, passwords, and dial-up phone numbers for outgoing connections.
All of this information is in plaintext.
An attacker with full access to an Ascend router can also use it to sniff the networks it is attached to.
Ascend routers have an extensive (and largely undocumented) debugging interface; functions are included in this interface to obtain hexadecimal dumps of raw Ethernet, ISDN, DS1, and modem traffic.
Affected Products:
- Ascend MAX 5.0.0.0Ap42
- Ascend Pipeline 5.0.0.0A
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