Rating:

# Kill

There is a broken `pcap` file, which we need to fix. Looks like the file was obtained using tool `dumpcap` on Mac OS X:

```
$ hexdump -C kill.pcapng | head
00000000 aa dd dd aa 8c 00 00 00 4d 3c 2b 1a 01 00 00 00 |........M<+.....|
00000010 ff ff ff ff ff ff ff ff 03 00 2f 00 4d 61 63 20 |........../.Mac |
00000020 4f 53 20 58 20 31 30 2e 31 31 2e 36 2c 20 62 75 |OS X 10.11.6, bu|
00000030 69 6c 64 20 31 35 47 31 30 30 34 20 28 44 61 72 |ild 15G1004 (Dar|
00000040 77 69 6e 20 31 35 2e 36 2e 30 29 00 04 00 34 00 |win 15.6.0)...4.|
00000050 44 75 6d 70 63 61 70 20 31 2e 31 32 2e 34 20 28 |Dumpcap 1.12.4 (|
00000060 76 31 2e 31 32 2e 34 2d 30 2d 67 62 34 38 36 31 |v1.12.4-0-gb4861|
00000070 64 61 20 66 72 6f 6d 20 6d 61 73 74 65 72 2d 31 |da from master-1|
00000080 2e 31 32 29 00 00 00 00 8c 00 00 00 01 00 00 00 |.12)............|
00000090 60 00 00 00 01 00 00 00 00 00 04 00 02 00 06 00 |`...............|
```

If we sniff some of our traffic, we can check if the header matches, but instead of `aa dd dd aa` the file starts with `0a 0d 0d 0a`.

```
$ dumpcap
Capturing on 'eth0'
File: /tmp/wireshark_eth0_20160914212455_WgZFXm.pcapng
Packets captured: 4
Packets received/dropped on interface 'eth0': 4/2 (pcap:1/dumpcap:0/flushed:1/ps_ifdrop:0) (66.7%)
```

```
$ hexdump -C /tmp/wireshark_eth0_20160914212440_jsZWs2.pcapng | head -1
00000000 0a 0d 0d 0a 7c 00 00 00 4d 3c 2b 1a 01 00 00 00 |....|...M<+.....|
```

After we edit the first four bytes and open the file with Wireshark, we read the flag in one of the streams (3).

Easier solution is to read the flag directly on these addresses:

```
006c7d0: ff e0 ba e0 4a 46 49 46 00 01 01 01 00 01 00 01 ....JFIF........
006c7e0: 00 00 ff fe 00 3d 66 6c 61 67 7b 72 6f 73 65 73 .....=flag{roses
006c7f0: 5f 72 5f 62 6c 75 65 5f 76 69 6f 6c 65 74 73 5f _r_blue_violets_
006c800: 72 5f 72 33 64 5f 6d 61 79 62 33 5f 68 61 72 61 r_r3d_mayb3_hara
006c810: 6d 62 61 65 5f 69 73 5f 6e 6f 74 5f 6b 69 6c 6c mbae_is_not_kill
006c820: 7d ff ed 00 9c 50 68 6f 74 6f 73 68 6f 70 20 33 }....Photoshop 3
```

Original writeup (https://github.com/73696e65/ctf-notes/blob/master/2016-ctf.csaw.io/forensics-50-kill.md).