I am trying to take part in a CTF challenge. I have a pcap file of a jpg file transfer. I know that the jpg starts with FF D8 FF and ends with FF D9.
The problem is that I have no idea how to extract the file itself.
The file is in here:
00000226 67 0d 0a 0d 0a ff d8 ff e0 00 10 4a 46 49 46 00 g....... ...JFIF.
00000236 01 01 00 00 01 00 01 00 00 ff db 00 43 00 03 02 ........ ....C...
..
00015617 d2 51 95 15 f7 e1 c0 d8 e9 6d 58 c8 07 71 c7 40 .Q...... .mX..q.#
00015627 3a 79 53 19 33 54 00 05 b4 92 07 33 5e af 54 2d :yS.3T.. ...3^.T-
00015637 1f ff d9 ...
As you can see it's mixed with 67 0d 0a 0d and the other information. I tried to copy the relevant parts and cut out the offset and ascii (?) section left and right with python and then imported the hexdump to this site to create a jpg of the hex dump.
Unfortunately that didn't work. The resulting image is extremely distorted and I can't read anything on it.
Does anyone have an advice? Not a full solution, just a tip so I can wrap my head around it myself.
Thanks.
Related
Has anyone seen (fixed?) a problem with strings of zeroes in audio data captured with the AL5645 codec microphone input on the Coral dev board? It's happening for me with default settings using arecord, as well as my python code using PyAudio. 16 bit (mono) samples, sample rates 16000Hz and 44100Hz. e.g. 83 ce 34 0b 09 3f 00 00 00 00 00 00 2b 0e 2b 0e b0 d0 5a b9 ee d9 00 00 00 00 75 44 75 44 75 44 ba 38 8a ff e6 c6 00 00 00 00 00 e7 00 e7 00 e7 85 26 f4 46 bc 2e
?
Cheers,
Mark
Sorry for the bad title but I don't know how else to phrase "follow".
I'm looking to remotely download a csv file from a website. I could do this by clicking the download button using RSelenium, but I've found that there's a direct link that will initiate the download for me. I.e. I could go to https://www.fake-website-url.com and click the download button, or I could just enter https://www.fake-website-url.com/exportcsv into my browser and it would automatically download.
I try not to use RSelenium whenever I can help it since it's clunky, but I'm not sure how to just initiate the download. Nothing from rvest stands out since I'm not actually reading html.
Basically, I'm looking for an R function like gotoURL('https://www.website.com/exportfullcsv) that will download the file just like it would if I entered the URL into my browser.
Since you said that you were able to find a direct URL, then the issue is not that the download failed, it's that you aren't accessing the content correctly.
I uploaded a small zip file to a personal website and ran this code:
dl <- httr::GET("https://.../sessions_tracker.zip")
dl
# Response [https://.../sessions_tracker.zip]
# Date: 2020-04-08 20:59
# Status: 200
# Content-Type: application/zip
# Size: 19.2 kB
# <BINARY BODY>
length(httr::content(dl))
# [1] 19184
19184 / 1000
# [1] 19.184 ### confirmation of download, this rounds to 19.2kB
head(httr::content(dl), n=80)
# [1] 50 4b 03 04 14 00 00 00 08 00 60 7e 7b 50 1e c3 ed e8 32 4a 00 00 fa b7 01 00 14 00 1c 00
# [31] 73 65 73 73 69 6f 6e 73 5f 74 72 61 63 6b 65 72 2e 63 73 76 55 54 09 00 03 53 83 7e 5e 5e
# [61] 01 85 5e 75 78 0b 00 01 04 d3 c6 2d 00 04 64 00 00 00 b4 5d
writeBin(httr::content(dl), "sessions_tracker.zip")
It's currently 04:40 AM and I am stuck on something I simply do not understand. I am trying to look up a domain's nameservers directly by using the DNS protocol. If I send a host -t ns google.com 1.1.1.1 and monitor it with Wireshark, I can see the full query of the DNS query. However, I cannot figure out, why some ASCII characters are used one time, but not another time. Here is an example:
0000 70 4d 7b 94 dd e0 00 d8 61 a9 c5 ec 08 00 45 00 pM{.....a.....E.
0010 00 38 d6 ff 00 00 80 11 9f 50 c0 a8 01 bb 01 01 .8.......P......
0020 01 01 e8 40 00 35 00 24 a0 19 9e f7 01 00 00 01 ...#.5.$........
0030 00 00 00 00 00 00 06 67 6f 6f 67 6c 65 03 63 6f .......google.co
0040 6d 00 00 02 00 01 m.....
In this DNS query, I am looking up the nameservers for google.com. The actual query starts at 06 07.
06 in ASCII is ACK/Acknowledgment.
Now, if we take a look at gmail.com instead:
0000 70 4d 7b 94 dd e0 00 d8 61 a9 c5 ec 08 00 45 00 pM{.....a.....E.
0010 00 37 d7 00 00 00 80 11 9f 50 c0 a8 01 bb 01 01 .7.......P......
0020 01 01 e8 58 00 35 00 23 8f cc 6f e2 01 00 00 01 ...X.5.#..o.....
0030 00 00 00 00 00 00 05 67 6d 61 69 6c 03 63 6f 6d .......gmail.com
0040 00 00 02 00 01 .....
the query starts at 05 67 instead.
05 is ENQ/Enquiry.
Why are they different? If I try to send 06 instead of 05 the DNS server gives me no response but Wireshark tells me:
Unknown extended label
I've seen 05, 06, and 09 so far. 09 is my biggest "wat" of all time, because it's a HT/Horizontal Tab.
Anyone with a lot of DNS knowledge who can help me here? I'm not looking for "just use dig/nslookup/host command". I'm currently trying to research a bit on the DNS protocol, and this is a thing I do not understand.
Good read where I got a lot of help: http://dev.lab427.net/dns-query-wth-netcat.html
For a binary protocols like this, you can't assume each byte corresponds to the matching ASCII character.
Take a look at section 4.1.2 of the DNS RFC (https://www.ietf.org/rfc/rfc1035.txt).
The domain name in a DNS request is broken up into "labels". For each label, the first byte is the length of the label, then the bytes for the string are written.
For your Google.com example, the labels are "google" and "com". The 06 is the number of bytes in the first label. This is followed by the bytes for "google". Then the 03 is the number of bytes in the "com" label. After the "com" bytes, the 00 byte is the NULL label to mark the end.
I'm trying to do some reverse engineering on my heating system. Monitoring the CAN BUS results in receiving hexademical strings, for example:
00 D0 68 D6 86 83 61 8F
61 C0 02 5C 12 B5 02 5C
12 78 04 39 04 03 05 02
05 C4 04 5C 12 5C 12 5C
12 5C 12 D0 68 00 00 00
00 18 08 37 D2 00 00 00
00 00 00 00 00 15 75 F2
F0 01 00 01 00 00 00 1F
I know that for example the temperature value of 22.5°C should be somewhere in there.
So far I have tried to look for the following conversions:
Possibility 1: ascii to hex
22.5 = 32 32 2E 35
Possibility 2: float to hex conversion
22.5 = 0x 41 b4 00 00
However none of these resulted in a match.
What would be other possibilities to converted a float to a hex string?
Thx
note: the given string is just a small part of my can sniffer so don't look for 22.5 in my given string here. I'm just looking for other possible conversions.
I started a thread in the NI support forums about my project, but my current problem is more broad than just driver writing in labview. I have an anemometer that uses a USB UART bridge
to interface with the computer. I asked Extech for any kind of documentation for and received only the communication protocol below.
Serial Communication Protocol
I encountered several problems working with this, so I took the software included with the anemometer and used portmon to sniff the commands going to and from, and here's where it gets worse. To simplify matters as best as I could, I only took ambient temperature readings. The following was what portmon captured when I used the manufacture's software to connect to the instument:
(This is the 'upload protocol' on the above protocol documentation)
AA 61 64 6A 67 08 40 00 40 00 01 00 00 C6 41 00 00 00 00 00 3C 1C C6 9A 19 99 42 00 3C 1C C6 00 00
AA 61 64 6A 67 08 40 10 40 00 01 7D 0C C6 41 00 00 00 00 00 3C 1C C6 39 1F 99 42 00 3C 1C C6 00 00
AA 61 64 6A 67 08 40 10 40 00 01 00 00 C6 41 00 00 00 00 00 3C 1C C6 9A 19 99 42 00 3C 1C C6 00 00
AA 61 64 6A 67 08 40 10 40 00 01 83 F3 C5 41 00 00 00 00 00 3C 1C C6 FB 13 99 42 00 3C 1C C6 00 00
This is slightly truncated, but the important parts should be there. The ambient temperature read about 76.5F at the time. So according to the documentation, this should be in the 10-13th bits, so I believe:
0000c641
7d0cc641
0000c641
83f3c541
To be the recorded ambient temperatures, but I have no idea how to read this. I see no reason why a conversion from Kelvin or Celsius would be necessary as there seems to be a bit for that in F1. Also of note is the fact that I get values completely different than anything documented for several fields, so either I'm reading something wrong or the documentation is just wrong. I haven't been able to get any more answers from the manufacturer about the protocol, so I have no idea why my data only half resembles what is expected.
41C60000 converts to 24.75 as an IEEE754 standard 32-bit single precision float. This looks like a Celsius value which would map to 76.55 F.
For the rest of the data you would have :
41C60000 = 24.7500000000000000000
41C60C7D = 24.7560977935791015625
41C5F383 = 24.7439022064208984375
I think that sorts out the endianness and formatting for you.