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Cisco AIM-CUE

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First post, by paleophyte

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I don't know if there is a better place on the forum for this (or I guess a better place on the Internet in general, for that matter)... if so, I haven't found it. I've recently been in to saving (or trying at least) some older enterprise hardware from the brink of extinction, and one device I'm attempting to rescue is an AIM-CUE, which is... basically a computer? It just lives inside of a router; it has CPU, memory, and a disk drive. It runs a Cisco-customized Linux variant, and it boots from an included Compact Flash card. The problem I'm running into is that these modules are fairly old now, and most of the Cisco branded CF cards are failing at this point. Which wouldn't be a big deal, except that when the module boots, it does some kind of check to see whether it's running on an actual Cisco CF card or not. If it's not the right card, it fails with this message:

Please enter '***' to change boot configuration:

Not a cisco supported CF. Please use cisco supported CF and reinstall the software.
System Halted.

I tried with a 1GB SanDisk card with the exact same result. I've also tried with larger Cisco branded CF cards (for example, I have a 4GB one that is fairly new), and that also fails with the same message, so it's not only looking for Cisco branded, but also of a specific size. I think the module originally supported options for 512MB or 1GB cards.

Entering three stars (***) takes you into a menu where you can boot from a TFTP server to reinstall the software. I'll attach the entire process of what a software reinstall looks like just in case that is helpful at all.

Anyone have any suggestions for ways I might attempt to subvert this check? Any guesses as to whether this is something that has been built into the OS or if it's part of the BIOS or something like that? I thought about a CF to SD adapter, but I assume I'd still need some way to emulate whatever attributes the device is looking for or skip the check. If it's in the OS, I should be able to put the card into another system and... edit... something... I'm just not sure where to start looking for something like this. Any tips/thoughts/ideas/suggestions would be greatly appreciated!

Reply 2 of 10, by paradigital

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It will likely be a simple hardware ID check that will be in the firmware of the CF card.

I’ve got a working AIM-CUE in my old CCNA voice lab somewhere.

I also have a fair number of smaller (256MB > 1GB) Cisco CF cards.

Reply 3 of 10, by paleophyte

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paradigital wrote on 2024-09-25, 17:17:

It will likely be a simple hardware ID check that will be in the firmware of the CF card.

I’ve got a working AIM-CUE in my old CCNA voice lab somewhere.

I also have a fair number of smaller (256MB > 1GB) Cisco CF cards.

Yeah, that’s what I was thinking. Know of any tools that allow viewing / changing this information?

Reply 4 of 10, by paleophyte

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DosFreak wrote on 2024-09-25, 14:29:

Have you tried formatting the card directly from the device or another cisco device?

I’ve not tried that yet. I can format it from the router itself and see if anything changes. I’d suspect not, but it’s worth a shot.

Reply 5 of 10, by paradigital

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Dug mine out of the loft, it still works fine in its 2811 home. Has the Cisco branded 1GB CF 17-7827-01 card in it.

The attachment IMG_4412.jpeg is no longer available

Reply 6 of 10, by paleophyte

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paradigital wrote on 2024-09-28, 11:43:

Dug mine out of the loft, it still works fine in its 2811 home. Has the Cisco branded 1GB CF 17-7827-01 card in it.

The attachment IMG_4412.jpeg is no longer available

I don’t suppose you’d be able to take an image of your card and put it on archive.org or something else, could you? One of my Cisco CF cards has completely failed, and the other one appears to be unreadable starting at sector 1,312,640 (at least, that’s where imaging fails)… I’m wondering if it will work on a generic card if I can manually dump an image onto the card…

Reply 7 of 10, by paradigital

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I will endeavour to do that as soon as possible. I need to find a CF reader first!

Reply 9 of 10, by NRoach44

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paleophyte wrote on 2024-09-25, 14:11:

Not a cisco supported CF. Please use cisco supported CF and reinstall the software.
System Halted.

Ohhh that's why that code is there.

I've "jailbroken" the NM-'(AIR-WLC,AON,CIDS,CE-BP-*CUE,NAM)' [1] to boot non-signed kernels (which would also probably apply here, but didn't know for sure why those strings were in the bootloader code.

If you're interested I can try patching that check out, but you'd need an original OS install / helper image to flash it.

[1]: https://blog.nroach44.id.au/012-cisco3745-aio-dialup.html

Reply 10 of 10, by NRoach44

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Just getting my thoughts together, since you're obviously hindered by the dead "disk".

1: Obtain unmodified helper image
2: Boot helper
3: Use helper to flash new bootloader (my test one perhaps)
4: Use my bootloader to boot a modified helper (e.g. this "debug mode" one https://blog.nroach44.id.au/files/jetfire/nam-debug.img )
5: Poke around?

Unfortunately I haven't found a signed helper that I can shell escape from yet.