1 % LVA-Feedback: mehr Freitext, weniger REP$x.$y !!! Diese Stuktur ist wirr und z.b. Failed attempts stehen an 3 unterschiedlichen stellen, obwohl sie doch alle irgendwie zusammenhängen -.-
3 \section{Exercise 1 - Task 1}
5 \fbox{\parbox{\textwidth}{
6 What is the IP address of the suspicious notebook?
9 The IP address of the suspicious notebook (our own IP address) is \emph{\textbf{192.168.67.37}}.
13 \fbox{\parbox{\textwidth}{
14 What is the IP address of the machine presumably leaking information?
17 The remote IP address is \emph{\textbf{192.168.67.83}}.
21 \fbox{\parbox{\textwidth}{
22 Give a detailed (but brief) explanation of these steps you carried out to filter irrelevant data (either Wireshark or Rapidminer).\\
23 Do also specify the keyworks and operators required.
26 The necessary wireshark filter expression is \emph{\textbf{ip.addr == 192.168.67.83}}.
30 \fbox{\parbox{\textwidth}{
31 Which features are not viable to mask a covert channel and could be removed from the analysis?\\
32 List the rejected features and provide short but meaningful reasons for rejection.
36 \item \emph{\textbf{No.}} is just the packet number in the pcap file.
37 \item \emph{\textbf{Source IP}} fixed value: \emph{\textbf{192.168.67.83}}
38 \item \emph{\textbf{Destination IP}} fixed value: \emph{\textbf{192.168.67.37}}
39 \item \emph{\textbf{Protocol}} fixed value: \emph{\textbf{UDP}}
40 \item \emph{\textbf{Length}} fixed value: \emph{\textbf{82}}
41 \item \emph{\textbf{TTL}} fixed value: \emph{\textbf{64}}
42 \item \emph{\textbf{Dest port}} fixed value: \emph{\textbf{118}}
43 \item \emph{\textbf{Flags}} fixed value: \emph{\textbf{n/a}}
44 \item \emph{\textbf{Frag offset}} fixed value: \emph{\textbf{0}}
47 Features containing fixed values have been rejected as one obviously cannot hide more than one bit of information in them.
51 \fbox{\parbox{\textwidth}{
52 From the remaining features, which ones are not viable to mask a covert channel and could be removed from the analysis?\\
53 List the newly rejected features and provide short but meaningful reasons for rejection.
56 We see that the source port changes only between transmissions. The transmission contains only one flow.\\
57 Therefore we can assume that the \emph{\textbf{source port}} can be ignored.\\
59 The next step was to apply the following filter in wireshark: \emph{\textbf{ip.addr == 192.168.67.83 and udp.srcport == 52899}}, export the result to a new pcap file and reload in wireshark (to reset the packet numbers) and export the pcap to csv.
63 \fbox{\parbox{\textwidth}{
64 Do you think that you have found the covert channel?\\
65 Give a detailed description of where the covert channel is occurring (feature value:covert symbol relationship) and provide a capture of the plot where the abnormal behaviour of the suspicious feature is isolated and clearly visible.
68 At first we wrote a decoder that made a diff between the current and the last csv line looking at \emph{\textbf{IP.ID}}.\\
69 Combined with the hint 8 bit ASCII we tried to extract full. The results did not made any sense.\\
71 After analysis with rapidminer we found that the timing diffrences were obviously not randomly distributed.\\
72 \includegraphics[width=0.8\columnwidth]{content/e11_timing.pdf}
74 So the hacky solution was to multiply the time-diff by 10 and cast the result to int. This resulted in a nice one bit/packet list which we quickly converted to 8 bit ascii.
78 \fbox{\parbox{\textwidth}{
79 Write in the report the formula of the deployed filter and the steps carried out to prepare the required file.
81 \emph{\textbf{Dest port == 118}} and later \emph{\textbf{ip.addr == 192.168.67.83 and udp.srcport == 52899}}.
85 \fbox{\parbox{\textwidth}{
86 Write in the report the decoded message. Explain clearly how you carried out the decoding task (step by step in a numbered list).
89 The message was \emph{\textbf{Starting transmission from Ministry of Cyber {\ucr}ffairs. (Agent Scott)Star{\ucr}i{\ucr}}}\\
90 By applying a corrective timing diffrence of 0.05 we can fully decode the message: \emph{\textbf{Starting transmission from Ministry of Cyber affairs. (Agent Scott)Startin}}\\
93 \begin{scriptsize}\begin{verbatim}
99 def somedecode(filename):
100 with open(filename, 'rb') as csvfile:
101 spamreader = csv.reader(csvfile, delimiter=',', quotechar='"')
106 for row in spamreader:
114 va = str(int((float(row[1])-float(last[1])-0.05)*10))
115 if va not in ["0","1"]:
121 print binascii.unhexlify('%x' % int(v, 2)),
126 if __name__ == "__main__":
127 somedecode("filtered.dehexed.csv")
128 \end{verbatim}\end{scriptsize}
132 \fbox{\parbox{\textwidth}{
133 Report briefly any additional comment or observation related to the exercise solving to be considered during the review of your exercise.
136 We had our wireshark misconfigured and were looking into the DSCP field for quite some time, before we realising that it was actually IP.ID.
139 \section{Exercise 1 - Task 2}
141 \fbox{\parbox{\textwidth}{
142 Give a detailed (but brief) explanation of the steps you carried out to filter irrelevant data (either Wireshark or Rapidminer). Do also specify the keywords and operators required.
145 Captured. Our new IP is \emph{\textbf{192.168.67.26}}.\\
147 Selected local network packets: \emph{\textbf{ip.src == 192.168.67.0/24 and ip.dst == 192.168.67.0/24}} and saved as separate pcap file and also exported the packets to csv.\\
149 In Rapidminer we analyzed the csv and removed our gateway (.1) and self (.26) as sources.\\
151 % TODO image:stream\_localnet.pdf
153 We get 4 network flows: The first from .83 to 80/udp, then from .82 to 443/udp, then .81 to 465/tcp, then .84 to 464/udp.\\
155 % TODO image:stream\_localnet\_ports.pdf
157 Filters for one complete transmission:
158 \emph{\textbf{udp.port == 58493 or udp.port == 45875 or tcp.port == 40875 or udp.port == 36842}}
160 % TODO: failed attempt
162 %%%%%%%%%%%%%%%%%%%%%
163 % WTF ?! % WTF ?! % WTF ?! % WTF ?! % WTF ?!
164 % WTF ?! % WTF ?! % WTF ?! % WTF ?! % WTF ?!
165 % WTF ?! % WTF ?! % WTF ?! % WTF ?! % WTF ?!
166 % WTF ?! % WTF ?! % WTF ?! % WTF ?! % WTF ?!
167 % WTF ?! % WTF ?! % WTF ?! % WTF ?! % WTF ?!
168 %%%%%%%%%%%%%%%%%%%%%
170 %filtered away nfs and ssh
171 %!(tcp.port == 666 || tcp.port == 2049)
174 %look at it via rapidminer
177 %((ip.addr eq 192.168.67.81 or ip.addr eq 192.168.67.82 or ip.addr eq 192.168.67.83) and ip.addr eq 192.168.67.37)
180 %look at it again via rapidminer
181 %image:stream\_better.pdf
183 %dest ports are always first 80/udp, then 443/udp, then 465/tcp
185 %filtered for one complete transaction
186 %tcp.port == 56533 or udp.port == 50293 or udp.port == 56040
189 %look at it again via rapidminer
190 %image:stream\_cool.pdf
192 %%%%%%%%%%%%%%%%%%%%%%%
196 \fbox{\parbox{\textwidth}{
197 Which features are not viable to mask a covert channel and could be removed from the analysis? List the
198 rejected features and provide short but meaningful reasons for rejection.
202 \item \emph{\textbf{No.}} (it is generated while monitoring and is strictly monotonically increasing by 1 with each packet)
203 \item \emph{\textbf{Time}} (packets arrive with almost equal delays)
204 \item \emph{\textbf{TTL}} (fixed value: \emph{\textbf{64}})
205 \item \emph{\textbf{Frag offset}} (fixed value: \emph{\textbf{0}})
208 We can also ignore \emph{\textbf{IP.Flags}} as they meet our expected distribution:
210 \item 0x0002: SYN (1x)
211 \item 0x0012: SYN,ACK (1x)
212 \item 0x0010: ACK (602x)
213 \item 0x0018: ACK,PSH (600x)
214 \item 0x0011: ACK,FIN (2x)
219 \fbox{\parbox{\textwidth}{
220 From the remaining features, which ones are not viable to mask a covert channel and could be removed
221 from the analysis? List the newly rejected features and provide short but meaningful reasons for rejection.
225 % TODO continue writing here.
227 not a high variance detected:
229 \item UDP Stream from 192.168.67.83:56040 to 192.168.67.37:80 %TODO fix
230 \item UDP Stream from 192.168.67.82:50293 to 192.168.67.37:443 %TODO fix
231 \item TCP Traffic between 192.168.67.81:56533 to 192.168.67.37:465 %TODO fix
232 \item UDP Stream from 192.168.67.84:36842 to 192.168.67.26:464
235 Length also does not vary very much:
237 \item Length 60 for Source Port 56040/udp
238 \item Length 60 for Source Port 52093/udp
239 \item Length 70 for ACK,PSH (600x), 74 for SYN (1x), 66 for ACK (1x) and 66 for FIN (1x) for Source Port 56533/tcp
240 \item Length 66 for ACK, 74 for SYN,ACK for Source Port 465/tcp
241 \item %TODO fix for sport 464
244 % TODO: failed attempt
245 %-> map in rapidminer ipid vs dscp
246 %-> every dscp has two ipid's? (ipid1 xor ipid2) or (ipid1 - ipid2) -> char
250 \fbox{\parbox{\textwidth}{
251 What is the IP address of the machine presumably leaking information?
254 Unknown, because we do have two shorter transmissions before a longer transmission from different source ips
256 % TODO: failed attempt 1 - nicht alles
257 Later the IP address turned out to be 192.168.67.84.
261 \fbox{\parbox{\textwidth}{
262 Do you think that you have found the covert channel?\\
263 Give a detailed description of where the covert channel is occurring (feature value:covert symbol relationship) and provide a capture of the plot where the abnormal behaviour of the suspicious feature is isolated and clearly visible.
266 Not yet. We do not know if the three transmissions are connected to each other.
268 % TODO: failed attempt 2 - dumm rum gesucht
269 Most likely it is in the DSCP field of the third transmission. (This also has responses from the local system)
271 Turned out that the 6 bits from the DSCP field in the 4. transmission just needed to be concatenated and then split into 8 bit chunks again.
275 \fbox{\parbox{\textwidth}{
276 Write in the report the decoded message. Explain clearly how you carried out the decoding task (step by step in a numbered list).
279 \emph{\textbf{Agent South already successfully infiltrated The minister's office. In the next step, we try to acquire data from the Ministry of Cyber Affair's office network. Stay tuned, I will keep you updated on the progress. (This message was sent by agent Scott)Agent South already successfully infiltrated The minister's office. In the next step, we try to acquire data from the Ministry of Cyber Affair's office network. Stay tuned, I will keep you updated on t}}\\
285 from pprint import pprint
289 with open('stream_data.txt', 'r') as infile:
293 bin = "{0:06b}".format(i)
296 bytelist = [ fullstr[i:i+8] for i in range(0, len(fullstr), 8) ]
300 for bchar in bytelist:
301 solution += chr(int(bchar, 2))
303 print ("%s" % solution)
304 print ("len: %d" % len(solution))
309 \fbox{\parbox{\textwidth}{
310 Report briefly any additional comment or observation related to the exercise solving to be considered during the review of your exercise.
314 % TODO: failed attempt 3 - config fail