JVN#49602378 SEIL/B1 authentication issue

Overview

SEIL/B1 contains an issue in the implementation of the PPP Access Concentrator (PPPAC) function, which may allow replay attacks to be performed during the authentication process.

Products Affected

SEIL/B1 firmware 1.00 through 2.52

Description

The PPP Access Concentrator (PPPAC) function within SEIL/B1 contains an issue in the CHAP and MS-CHAP-V2 authentication processes, the same challenge value is repeatedly used for each authentication attempt.

Impact

A third party may be able to perform replay attacks. As a result, the third party may gain access to the network.

According the developer, when L2TP/IPsec is being used, the authentication challenges are protected by the encryption provided by IPsec, and therefore the probability of being affected by this issue are reduced.

Solution

Update the Software
Update to the latest version according to the information provided by the developer.
This vulnerability has been addressed by firmware 2.60 that was released on December 1, 2009.

Vendor Status

Vendor	Status	Last Update	Vendor Notes
Internet Initiative Japan Inc.	Vulnerable	2009/12/09

References

JPCERT/CC Addendum

Vulnerability Analysis by JPCERT/CC

Analyzed on 2009.12.09

Measures	Conditions	Severity
Access Required	Routed - can be attacked over the Internet using packets	High
Authentication	None - anonymous or no authentication (IP addresses do not count)	High
User Interaction Required	None - the vulnerability can be exploited without an honest user taking any action	High
Exploit Complexity	Low-Medium - some expertise and/or luck required (most buffer overflows, guessing correctly in small space, expertise in Windows function calls)	Medium-High

Description of each analysis measures

Credit

Other Information

JPCERT Alert
JPCERT Reports
CERT Advisory
CPNI Advisory
TRnotes
CVE	CVE-2009-4409
JVN iPedia	JVNDB-2009-000079