Author Topic: Hacking SDS1102CML - boot logo  (Read 2194 times)

0 Members and 1 Guest are viewing this topic.

Offline vale_sarbu

  • Newbie
  • Posts: 2
  • Country: ro
Hacking SDS1102CML - boot logo
« on: April 04, 2017, 09:55:13 am »
Hello everybody. I'm new to the forum so this is my first post.

Last night I updated my SDS1102CML to Lecroy firmware and noticed that the same logo appeared during boot.

Things to work with: - Someone pointed out that the CFG file contains the Boot image
Hints: Opening the CFG file you can see the name Siglent in a few places (Eg: se–golonhceT tne“giS.SDS -AKA:  SDS Sig"ent Technolog-es)
So onto the reverse engineering...

If you alter the file it will give you a integrity error.
- First test : increase one byte by 1 and decrease the next by 1. - Passed file integrity so it's a Checksum
- Look for the Image in the file - It's 480x234 - begins at offset 0xD8 ends at 0x52518 and is a 24bit bitmap - 3 bytes per pixel
- Replaced the image with a same sized picture:
    -Make checksum equal to 8 bit total - not working
    -16 bit checksum - still not working
    -24 bit working

 (For reference try keeping the checksum of the image 0xC703A1)

Then compared the CML and CNL versions, they have the same image logo with a few differences:
  -CNL  @ 0x94 has a 0, CML has a 1 (CML has +1)
  -CNL  @ 0xD7 has a C6, CML has a C5 (CML has - 1)
  -That means that until 0x52518 (where the image ends) checksum shoud be identical for both scopes
  -After the end of the image there are two bytes that are in fact reverse order checksum -
    CML - 96 8D
    CNL - 9B F8
  -Difference between these is the same as the difference between the two footers (IN REVERSE 0x056B) so it seems like it's trying to maintain a constant total checksum. (maybe keeps a total Chksum of 3C88700)
Conclusion:
 - You can change the image if you maintain the Checksum without any risk of damage
 - Also change the name of the device - same condition applies

If you have any suggestions / ideas for future  or your own research please feel free to post.
Will post images of modified splash screen this evening.
 
The following users thanked this post: tautech

Offline vale_sarbu

  • Newbie
  • Posts: 2
  • Country: ro
Re: Hacking SDS1102CML - boot logo
« Reply #1 on: April 04, 2017, 06:46:03 pm »
I've made the picture, sorry Keithley  for being used with d**kbutts, I had no inspiration at the moment.
 
The following users thanked this post: thm_w, Deuze

Online tautech

  • Super Contributor
  • ***
  • Posts: 19394
  • Country: nz
  • Taupaki Technologies Ltd. NZ Siglent Distributor
    • Taupaki Technologies Ltd.
Re: Hacking SDS1102CML - boot logo
« Reply #2 on: April 04, 2017, 07:00:48 pm »
I've made the picture, sorry Keithley  for being used with d**kbutts, I had no inspiration at the moment.
That's funny, thanks.  :-DD

Could be the start of some competition, the funniest screen on your DSO.

Welcome to the forum.
Avid Rabid Hobbyist
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf