RE: Serious flaw in Linksys wireless AP password security Aug 16 2005 06:59PM
Robert Thompson Jr. (rthompson columbiabank com)
Thank you for the link. I appreciate it.

After reading through it, I am beginning to see where I may have
misunderstood what you were getting at.

When I was attempting to get into the router, with WZC set open, and
encryption was enabled on my router, but not on my nic, there was no

And with a wrong key, no connecting.

BUT - one thing that I did not do, was attempt to connect to the router
via WZC with the encryption turned ON but with no key supplied. I
always had a key loaded should the encryption be enabled.

I will test encryption on with no key when I get home tonight and see
what happens. Unfortunately, I will have to flash back down to the
4.50.6 firmware, BUT I'm curious.

Again, thank you for the link...

-----Original Message-----
From: Steve Scherf [mailto:steve (at) moonsoft (dot) com [email concealed]]
Sent: Tuesday, August 16, 2005 11:00 AM
To: Robert Thompson Jr.
Cc: Steve Scherf; bugtraq (at) securityfocus (dot) com [email concealed]
Subject: Re: Serious flaw in Linksys wireless AP password security

FYI, the problem I reported has been reproduced over at Broadband


Steve Scherf
steve (at) moonsoft (dot) com [email concealed]

On Mon, Aug 15, 2005 at 03:42:03PM -0700, Robert Thompson Jr. wrote:
> From: "Robert Thompson Jr." <rthompson (at) columbiabank (dot) com [email concealed]>
> Subject: RE: Serious flaw in Linksys wireless AP password security
> Date: Mon, 15 Aug 2005 15:42:03 -0700
> To: Steve Scherf <bugtraq (at) moonsoft (dot) com [email concealed]>, bugtraq (at) securityfocus (dot) com [email concealed]
> When upgrading my WRT54GS (v 1.0) router to the 4.50.6 and 4.70.6
> firmwares, I experienced no such authentication problems.
> If the router was set wide open, I could connect without
> As soon as I specified WPA-PSK on the router, in order for me to
> connect via the NIC I absolutely had to have the WZC configured for
> WPA-PSK (TKIP or AES accordingly) and HAD to have the correct password

> configured as well. (And the SSID of course...)
> If the proper settings were not configured into the WZC after enabling

> WPA-PSK, I was not able to connect to the router.
> I am certain of these details as I was trying to get the WPA2 feature
> to work on my NIC that didn't have WPA2 certified drivers at the time.

> I ended up trying every damned near possible configuration before
> realizing that it was my drivers that weren't working on my NIC before

> having to settle with just WPA until Linksys updated their drivers on
> their website...
> Though, since we are on the subject of the WRT54GS router. The 4.50.6

> and 4.70.6 firmwares enable the WPA2 feature. AND Linksys was kind
> enough to finally release WPA2 certified drivers for the WPC54GS NIC's

> (and I am assuming the WPC54G) as well. So if you haven't updated,
> you may want to condsider doing so for the increased security.
> Rob.
> -----Original Message-----
> From: Steve Scherf [mailto:bugtraq (at) moonsoft (dot) com [email concealed]]=20
> Sent: Sunday, August 14, 2005 12:53 AM
> To: bugtraq (at) securityfocus (dot) com [email concealed]
> Subject: Serious flaw in Linksys wireless AP password security
> It appears that firmware version 4.50.6 for the Linksys WRT54GS
> (hardware version 1) wireless router allows wireless clients to
> connect and use the network without actually authenticating. With WPA
> Personal/TKIP authentication enabled, the unit allows both clients
> using encryption with the correct settings and key, and clients not
> using any encryption. It disallows clients attempting to use
> encryption with the wrong settings and/or key.
> In other words, even if you think you've secured your wireless network

> from unauthorized access, anyone can access it. It actually shows up
> as having no password security on a Macstumbler scan, which is how I
> noticed the problem.
> I verified that anyone can access the network without needing to know
> the key.
> I did not check security modes other than WPA/TKIP. Other modes may
> have different behavior. Changing the "Authentication Type" setting
> had no effect on this problem. I believe it should be set to "Shared
> Key", but the setting used does not appear to matter.
> I only verified the problem on firmware 4.50.6. It is unknown if other

> firmware versions exhibit the problem. However, at least one older
> firmware does not exhibit the problem, as my router functioned
> correctly until I updated to 4.50.6.
> The problem appears to be fixed in version 4.70.6. No expliclit notice

> of this problem or the fix appears in the release notes for version
> 4.70.6.
> Strangely, the "Authentication Type" must be set to "Auto" for the
> unit to function properly. Should it be set to "Shared Key", which one

> might expect to be the correct value, the wireless functionality
> appears to be entirely disabled.
> It is unknown if this problem is seen with other hardware versions, or

> with other models. I suspect it may, given the similarity between many

> of the Linksys models and their firmware.
> --
> Steve Scherf
> bugtraq (at) moonsoft (dot) com [email concealed]

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