Indonesian J our nal of Electrical Engineering and Computer Science V ol. 19, No. 2, August 2020, pp. 1036 1047 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v19i2.pp1036-1047 r 1036 Countermeasur es against darknet localisation attacks with pack et sampling Masaki Narita, K eisuk e Kamada, Kanay o Ogura, Bhed Bahadur Bista, T oy oo T akata Graduate School of Softw are and Information Science, Iw ate Prefectural Uni v ersity , Japan Article Inf o Article history: Recei v ed Jan 2, 2020 Re vised Mar 3, 2020 Accepted Mar 17, 2020 K eyw ords: Darknet monitoring Localisation attack P ack et sampling Security ABSTRA CT The darknet monitoring system consists of netw ork sensors widely deplo yed on the Internet to capture incoming unsolicited pack ets. A goal of this system is to analyse captured malicious pack ets and pro vide ef fecti v e information to protect re gular non- malicious Internet users from malicious acti vities. T o pro vide ef fecti v e and reliable information, the location of sensors must be concealed. Ho we v er , attack ers launch localisation attacks to detect sensors in order to e v ade them. If the actual location of sensors is re v ea led, it is almost impossible to identify the latest tactics used by attack ers. Thus, in a pre vious study , we proposed a pack et sampling method, which samples incoming pack ets based on an attrib ute of the pack et sender , to increase tolerance to a localisation attack and maintain the quality of information publicised by the system. W e were successful in countering localisation attacks, which generate spik es on the publicised graph to detect a sensor . Ho we v er , in some cases, with the pre viously propos ed sampling method, spik es were clearly e vident on the graph. Therefore, in this paper , we propose adv anced sampling methods such that incoming pack ets are sampled based on multiple attrib utes of the pack et sender . W e present our impro v ed methods and sho w promising e v aluation results obtained via a simulation. Copyright © 2020 Insitute of Advanced Engineeering and Science . All rights r eserved. Corresponding A uthor: Masaki Narita, Graduate School of Softw are and Information Science, Iw ate Prefectural Uni v ersity , 152-52 Sugo, T akiza w a, Iw ate 020-0693, Japan. Email: narita m@iw ate-pu.ac.jp 1. INTR ODUCTION The Internet has become an indispensable resource for most people. Ho we v er , a v arious mal w are is deplo yed to cause c yber attacks that seriously threaten the safe and reliable use of the Internet, for e xample stealing confidential personal d a ta or launching Denial-of-Service (DoS) attacks on specific corporate enter - prises to hinder their ability to pro vide services [1]. A Symantec [2] sho ws that 4,818 unique websites were compromised e v ery month in 2018. W ith data from a single credit card being sold for up t o $45 on under ground mark ets, just 10 credit cards stolen from compromised websites could result in a yield of up to $2.2 million for c yber criminals each month. Cyberattacks primarily e xploit softw are vulnerabilit ies [3, 4]. Thus, i t is essential to find and manage such vulnerabilities at an early stage to pre v ent v arious types of damage, e.g., re v ealing confidential information or financial harm to both corporate enterprises and general users. Darknet monitoring systems are de v eloped to find softw are vulnerabilities and identify the latest meth- ods used by attack ers. An o v ervie w of a darknet monitoring system is sho wn in Figure 1. A darknet monitoring system comprises multiple netw ork de vices, i.e., sensors, that are deplo yed in unused IP address space on the Internet. Note that these sensors are configured to capture only incoming pack ets; the y do not pro vide an y out- going services. Such sensors may recei v e unsolicited pack ets when the y are directly connected to the Internet. J ournal homepage: http://ijeecs.iaescor e .com Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 1037 Sensors distrib uted in darknet space capture incoming unsolicited pack ets. T ypically , pack ets do not arri v e in unused address space, i.e., darknet. Thus, we can infer that pack ets arri ving in these unused address spaces, which are v alid and routable, are lik ely malicious. Or g anisations that operate darknet monitoring systems col- lect and analyse these malicious pack ets. Usually , the analysis results, which can pro vide ef fecti v e information to protect re gular , non-malicious Internet users from malicious acti vities, are made publicly a v ailable. Users Data Center Sensors Malicious Packets Monitored Results Figure 1. Ov ervie w of darknet monitoring system T o pro vide ef fecti v e and reliable information, the location of darknet sensors must be concealed be- cause attack ers launch localisation attacks to detect the sensors’ IP addresses in order to e v ade them. If the IP addresses are re v ealed to attack ers, it is almost impossible to identify and analyse ne w malicious attack methods [5]. In addition, the sensors thems elv es may be tar geted by DoS attacks. When attack ers initiate a localisation attack, the y masquerade as general Internet use rs. T o detect sensors, the y misuse information pro vided by or g anisations operating a darknet monitoring system. Thus, if or g anisations release time-series graphical information without taking countermeasures to protect the information, attack ers can use the publi- cised graph to detect a sensor . In a pre vious study , we proposed a pack et sampling method, which samples captured pack ets based on an attrib ute of the pack et sender , to increase localisation attack tolerance and to en- sure the quality of information pro vided by a darknet monitoring s y s tem in our w ork [6, 7]. W e were relati v ely successful in countering localisation attacks, which generate spik es on the publicised graph to detect a sensor . Ho we v er , in some cases, une xpected spik es that could indicate the location of a sensor appeared in the graph. Therefore, here, we propose adv anced sampling methods whereby incoming pack ets are sa mpled based on multiple attrib utes of the pack et sender . Note that the proposed method e xploits kno wledge g ained from our pre vious w ork. A performance e v aluation w as conducted by simulating attack ers’ tactics and applying the proposed methods. W e used actual captured pack ets pro vided by the Nicter [8, 9] darknet project operated by the Japanese National Institute of Information and Communi cations T echnology (NICT). In addition, we also discuss the de gradation of publicised information by sampling captured pack ets compared to a no sampling case. In this paper , we present our impro v ed methods and sho w a promising e v aluation result . This p a per is a re vised and e xpanded v ersion of a paper entitled A Study of P ack et Sampling Methods for Protecting Sensors Deplo yed on Darknet” presented at 19th International Conference on Netw ork-Based Inform ation Systems (NBiS 2016) [7]. 2. RELA TED W ORK A wide v ariety of darknet monitoring systems are operated all o v er the w orld to identify and under - stand the latest at tack trends on the Inter n e t [10, 11]. The NICT NICTER project has man y user interf ace s. F or e xample, Cube dra ws a cubical object in the centre of a windo w and maps captured pack ets on the object based on the source and destination of arri v ed pack ets. Atlas maps captured pack ets on a w orld map and indicates in real time the count ries that sends malicious pack ets to Japan. In addition, NICTER counts captured pack ets by country of origin and classifies pack ets as TCP or UDP . This is a v ailable on the NICTER W eb [12]. As another e xample, the Japanese National Police Agenc y operates @police [13], a darknet monitoring system that col- lects fire w all and intrusion detection system log data at the netw ork entry g ate w ay of institutions af filiated with the police. @police pro vides security-related information in the form of ti me-series graphs and tables on their web site. DShield [14], a community-based fire w all log correlation system, recruits v olunteers from across the w orld. The v olunteers pro vide fire w all logs that are used to analyse attack trends. DShield is the w orld’ s lar gest darknet community . The Cooperati v e Association for Internet Data Analysis, CAID A [15, 16], man- Countermeasur es a gainst darknet localisation attac ks... (Masaki Narita) Evaluation Warning : The document was created with Spire.PDF for Python.
1038 r ISSN: 2502-4752 ages the Uni v ersity of California, San Die go’ s Netw ork T elescope’ s Internet traf fic monitoring system. This system dominates an entire globally routed /8 netw ork that comprises approximately 1/256 of all IPv4 Internet addresses. The system captures all incoming pack ets to that address space. Ho we v er , attack ers launch localisation attacks ag ainst darknet monitoring systems to detect and bypass sensors. Shinoda et al. [17] and Bethencourt et al. [18] reported that, to detect sensors, an attack er can send a lar ge number of probing pack ets to suspicious netw ork that includes a sensor preliminary in the short term to detect sensors. Subsequently , attack ers af firm the presence of sensors if sharp spik es appear on the time- series graph publicised by the tar geted system. Y u et al. [19–21] and our w ork [22] introduced a localisation attack inspired by spread spectrum technology . This method increases attack stealth and can detect sensors with lo w probing pack ets by sending probing pack ets synchronised with the v alue of a PN code sequence. If the IP addresses of deplo yed sensors are re v ealed by a localisation attac k , attack ers can bypass the sensors intentionally and launch malicious attacks on the Internet. Consequently , identifying the latest attack trends becomes dif ficult. In addition, the sensors themselv es may be e xposed to obstinate DoS attacks. Basically , attack ers infer sensor IP addresses by in v estig ating the publicly a v ailable data pro vided by agencies that operate darknet monitori ng systems. In short, attack ers put a mark on upcoming publicised data and v erify the presence of the mark to detect a sensor . If countermeasures are not implemented, attack ers could e xploit publicised data and easily detect sensors. Thus, establishing countermeasures ag ainst localisation attacks is imperati v e. V iecco indicated and emphasised the usefulness of pack et sampling techniques for captured pack ets as a countermeasure to localisation attacks [23] . Ho we v er , the y only consider a theoretical frame w ork. The y do not propose a functional sampling method and ha v e not conducted a numerical v alidation. Thus, we propose a pack et sampling method wherein capturing pack ets are sampled based on an attrib ute of the pack et sender . Sampling is essentially a process that selects a representati v e subset of indi viduals from an entire population. W e ensure that pack et sampling alle viates the influence of probing pack ets sent by attack ers in open publicised data and obtain tolerance to a localisation attack. 3. LOCALISA TION A TT A CK BY GENERA TING SPIKES In this section, we describe the localisation attack concept, which generates spik e on the pu bl icised graph. This is based on the w ork by Shinoda et al. [17] and Bethencourt et al. [18]. Shinoda et al. [17] referred to a direct and intentional detecting sensor acti vity as marking. The y also defined spik es used for marking as a mark er . In this paper , we use these terms in the same manner . An o v ervie w of the localisation attack is sho wn in Figure 2, and we e xplain the procedures in the follo wing. 3) Identify Marker 4) Update   Address List Data Center Attacker Address List Sensors 2) Send Marker 1) Preliminary Survey Publicized Monitored  Result Figure 2. Ov ervie w of localisation attack (a) Attack ers preliminarily narro w do wn lists of suspicious tar get netw orks that include a sensor by analysing materials on the web and obtaining handouts distrib uted in w orkshops by an operating or g anisation of the tar get darknet monitoring system. The in v estig ated results are preserv ed by attack ers and become lists of suspicious IP addresses acting as sensors on the Internet. Then, the attack ers select a range of IP addresses from the lists and initiate a localisation attack by sending mark ers. (b) Attack ers send mark ers o v er a short period to suspicious netw orks that include sensors, i.e., marking. If the sensor recei v es pack ets in a short period, a discriminating spik e appears in the time-series graph publicised by the tar get darknet monitoring system. Indonesian J Elec Eng & Comp Sci, V ol. 19, No. 2, August 2020 : 1036 1047 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 1039 (c) Attack ers masquerading as general and good Internet users access a website operated by the or g anisation running t he tar get darknet monitoring system. The y v erify the presence of a sensor in a tar get netw ork by identifying the mark er trace in the system’ s publicised time-series graph. (d) F ollo wing the result of procedure 3), the attack ers update the lists of suspicious IP addresses. The y precisely identify a sensor’ s IP address by repeating procedures (b) through (d). The abo v e procedures summarise localisation attacks, which produce spik es on a publicised graph. Since mark ers are sent as standard pack ets generated by a port scan, i t is dif ficult to distinguish between mark ers and other pack ets. As a result, a darknet monitoring system unintentionally pro vides instructi v e feedback to attack ers by publicising monitored results based on an all captured pack ets (including mark ers). 4. PR OPOSED P A CKET SAMPLING METHODS W e ha v e pre viously proposed a pack et sampling method that samples incoming pack ets based on an attrib ute of the pack et sender to increase tolerance to localisation attacks in our w ork [6]. Here, we propose tw o adv anced sampling methods that sample incoming pack ets based on multiple attrib utes of pack ets sender based on our pre vious w ork. 4.1. Method 1: Sampling captur ed pack ets by f ocusing on arri v al time and sour ce IP addr ess Initially , we determine the timing of pack et capture using random numbers. This is similar to our pre vious w ork, which uses pack et arri v al time. Consequently , using random numbers mak es it dif ficult for attack ers to infer when sensors capture pack ets. In addition, we k eep captured pack ets in chronological order . This contrib utes to tolerating localisation attacks. Ho we v er , successfully pre v enting a localisation attack is a matter of probability . In the w orst case, each sensor may capture all pack ets sent by attack ers based on the time selected by random numbers. Thus, as a second step, we also sample captured pack ets based on source IP address. Generally , global IP addresses are administrated by a re gistration system. Users of a global IP addres s must re gister a certain amount of identity information to WHOIS [24]. WHOIS informati on identifies which IP addresses are assigned to which country; thus, it is easy to access information about where captured pack ets originated. As sho wn in Figure 3 pro vided by Japanese National Police Agenc y [25], the ratio of source country of captured pack ets is greatly biased to w ard se v eral countries. W e assume that attack ers manipulate multiple hosts in a botnet to send mark ers when the y attempt a localisation attack. If the botnet comprises e xploited hosts whose source IP addresses are biased to w ard se v eral countries, sampling captured pack ets uniformly in terms of source countries reduces a spik e produced by attack ers on a publicised graph e v en with the containing mark ers in the time selected by random numbers. CN US TW RU DE JP HK TR KR NL Others Figure 3. Ratio of source country of captured pack ets The procedure for sampling method 1 is descri bed as follo ws. W e use GeoIP [26] to map the source IP address of captured pack ets to a country . Pr ocedur e 1: Determine Captur e T ime: (a) Configure parameters m and n as 0 m < n 60 . Hereafter , ( m; n ) denotes the range of random numbers. (b) Di vide captured pack ets into separate data per hour . The data are denoted :::; D i 1 ; D i ; D i +1 ; ::: . Gen- erate l random numbers for each D i . Note that l 2 [ m; n ] . Countermeasur es a gainst darknet localisation attac ks... (Masaki Narita) Evaluation Warning : The document was created with Spire.PDF for Python.
1040 r ISSN: 2502-4752 (c) Generate distinct l random numbers r j under follo wing conditions: 1 j l and 0 r j < 60 . (d) Sample pack ets arri v ed at k minutes at each D i , k 2 f r 1 ; r 2 ; :::; r l g . Pr ocedur e 2: Sample P ac k ets whose Countries ar e Distrib uted Equally: (a) Identify originating country by referencing the source IP address of a captured pack et. (b) Sample or discard pack ets based on the result of (a). a. Sample a pack et if it has not been captured from the identified country . b . If a pack et has been captured from the identified country , sample it as long as pack ets sent from the country are belo w predefined threshold 1 ; otherwise, discard the pack et. (c) Reset the list of the sampled country per hour . 4.2. Method 2: Sampling captur ed pack ets according to arri v al time and time-to-li v e In method 2, we initially determine pack et capture timing using random numbers (similar to method 1). W e then sample captured pack ets based on T ime-to-Li v e (TTL). TTL is a configured v alue in an IP header to pre v ent an endless loop of pack ets caused by misconfiguration in the netw ork. The TTL v alue is reduced sequentially when a pack et mo v es through a router . The corresponding pack et is discarded when the TTL v alue is reduced to zero. Generally , the initial TTL v alue is defined by an operating system as sho wn in T able 1. T able 1. Initial TTL v alue of major operating systems Operating System Initial TTL V alue UNIX 255 W indo ws 128 Linux 64 Thus, TTL can be used to infe r the number of routers pas sing pack ets along a communication path, and we can use it as an inde x of distance in a netw ork. Similar to method 1, if the source distance of captured pack ets is greatly biased, we belie v e sampling captured pack ets uniformly in t erms of the number of netw ork hops reduces a spik e produced by attack ers on a publicised graph. The procedure of sampling method 2 is described as follo ws. Pr ocedur e 1: Determine Captur e T ime: (a) Configure parameters m and n as 0 m < n 60 ( ( m; n ) denotes the range of random numbers). (b) Di vide captured pack ets into separate data per hour . The data is denoted :::; D i 1 ; D i ; D i +1 ; ::: . Generate l random numbers at each D i . Note that l 2 [ m; n ] . (c) Generate unique l random numbers r j under follo wing conditions, 1 j l and 0 r j < 60 . (d) Sample pack ets arri v ed at k minutes at each D i , k 2 f r 1 ; r 2 ; :::; r l g . Pr ocedur e 2: Sample P ac k ets Uniformly in T erms of the Number of Network Hops: (a) Infer the number of netw ork hops according to the TTL v alue. If the captured TTL v alue is t 1 , we obtain t 2 because t 2 is greater than the v alue of t 1 and less than the minimum v alue listed in T able 1. W e define the netw ork hops as t 2 t 1 . (b) Sample or discard pack ets based on the result of 1). a. If the number of netw ork hops has not been captured, sample it. b . If the number of netw ork hops has been captured, sample it as long as the number of netw ork hops is less than predefined threshold 2 ; otherwise, discard it. (c) Reset the list of the number of netw ork hops per hour . 5. PERFORMANCE EV ALU A TION 5.1. Ev aluation of tolerance to localisation attack 1) Assumption: W e simulated a localisation attack (Section 3.) and e v aluated the ef fecti v eness of the proposed methods to coun t eract the attack. Simulations were performed using a dataset [27] that includes pack ets cap- tured in No v ember of 2015. The dataset w as pro vided by NICTER (a darknet monitoring system operated in Japan). Assumptions about the tar get darknet monitoring system and localisation at tack are described in the follo wing. Indonesian J Elec Eng & Comp Sci, V ol. 19, No. 2, August 2020 : 1036 1047 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 1041 (a) Assumption about tar get darknet monitoring system: In this simulation, the tar get darknet monitoring system captures pack ets at each port. Then, the system publicises and updates the monitored results at the same time interv al. As sho wn in Figure 4, the transi- tion of the number of pack ets captured by the system is plotted in a time-series graph per hour within the compass of one week. Here, the Y -axis i s the nu m ber of pack et s, and the X-axis is elapsed time. Note that an y general Internet user can ac cess the publicised result; thus, malicious users can access the same information. Figure 4. Graph publicised by tar get darknet monitoring system (b) Assumption about localisation attack: W e assume that an attack er sends mark ers to the tcp port 445 as the destination. In this simulation, the number of pack ets arri ving at tcp port 445 dra ws a relati v ely smooth graph compared to that of other ports as sho wn in Figure 4; thus, we consider that attack ers are easy to identify their spik es on the publicised graph. In other w ords, we belie v e that this port is suitable for a loca lisation attack. W e also assume tw o groups of botnets, i.e., botnets A and B. These botnets are descri bed in T ables 2 to 5. Botnet A comprises e xploited hosts whose source IP addresses and netw ork hops are greatly biased, and botnet B is the group that is the same assumption in our pre vious w ork for the comparison. The number of sent pack ets, mark ers, duration of pack et sending and time interv al are sho wn in T able 6. T able 2. Breakdo wn of botnet A in terms of source countries Country (Code) The Number of Hosts CN 2 US 1 R U 1 T able 3. Breakdo wn of botnet A in terms of netw ork hops The Number of Netw ork Hops The Number of Hosts 18 2 15 1 12 1 T able 4. Breakdo wn of botnet B in terms of source countries Country (Code) The Number of Hosts CN 7 US 3 TW 2 NL 2 IN 1 KR 1 TR 1 R U 1 FR 1 MX 1 Countermeasur es a gainst darknet localisation attac ks... (Masaki Narita) Evaluation Warning : The document was created with Spire.PDF for Python.
1042 r ISSN: 2502-4752 T able 5. Breakdo wn of botnet B in terms of netw ork hops The Number of Netw ork Hops The Number of Hosts 18 4 19 4 15 2 17 2 20 1 21 1 16 1 14 1 22 1 12 1 28 1 27 1 T able 6. Marking parameters Destination Port 445/tcp The Number of Sending P ack ets 3,000 The Number of Mark ers 4 T ime Interv al among Markings 20 hours Duration of Marking within 1 minute 2) How to Determine Mark er s by Attac k er s: After attack ers attempt marking, the y masquerade as good Internet users and access a darknet monitoring system to identify their mark ers on a publicised graph to determine the presence of a sensor . Here, the attack ers must determine whether identified mark ers, i.e., spik es, on the graph were generated by themselv es. Note that we assume the attack ers determine their mark er using an outlier detection method. If the spik es are identified as a statistical outlier , the attack ers can identify the spik es as their o wn mark ers. In our e v aluation, we adopted the most general statistical method, i.e., the 2 outlier test. Figure 5 sho ws a simulated graph where attack ers insert four mark ers. If or g anisations operating a darknet monitoring system pro vide the graph as is without implementing countermeasures, attack ers can acquire adv antageous feedback, and a sensor’ s IP address can be disco v ered easily . Figure 5. Mark ers generated by attack ers 5.2. Inf ormation quality e v aluation Sampling is essentially a process that decimates a p a rt from entire and complete information. Thus, it is necessary to consider de gradation of information quality caused by a darknet monitoring system when using a sampling method. Therefore, we e v aluated the proposed methods in terms of information quality in sampling and no sampling cases. W e compared quality obtained before and after sampling i n well-kno wn publicised formats (time-series graph and table). 1) Rate of Concor dance of Most Accessed P ort: Darknet monitoring systems generally publicise the most accessed top 10 port numbers on their websites in table form. The most accessed top 10 port numbers are Indonesian J Elec Eng & Comp Sci, V ol. 19, No. 2, August 2020 : 1036 1047 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 1043 destination ports that atta ck ers intend to e xploit. Here, we assumed tw o sets including the top 10 port numbers: set X represents results obtained without sampling, and set Y represents results with sampling. W e then e v aluated the rate of concordance of these tw o sets. T o e v aluate the concordanc e rate of the tw o sets, we computed Simpson’ s coef ficient as follo ws: S im = j X \ Y j min ( j X j ; j Y j ) : 2) Similarity of T ime-series Gr aph: Darknet monitoring systems publicise the amount of arri ving pack ets at each port as a ti me-series graph on their website. W e compared a time-series graphs obtained without sampling f X u g and with sampling f Y u g . W e adopted the Bhattacharyya coef ficient L as an inde x to compute the similarity of these tw o graphs. L = m X u =1 p X u Y u ; m X u =1 X u = m X u =1 Y u = 1 ; (0 L 1) : The Bhattacharyya coef cient is essentially an inde x used to compute the similarity of histogram s. W e define the v alue of 1 L as the discrepanc y of graphs, where tw o graphs are increasingly similar as the v alue approaches zero. 6. RESUL TS AND DISCUSSION The e v aluation results are sho wn in T ables 7 to 11. The number of mark ers in each table r epresents the number of spik es that attack ers successfully identified in the publicised graphs. T able 7 sho ws the results obtained by our pre vious method. The other tables sho ws the results obtained by the proposed methods. Com- pared to the pre vious met ho d, the proposed sampling methods increased the tolerance to localisation attacks if we focus the number of appearing mark ers. Ho we v er , relati v e to graph discrepanc y and concordance rate of the accessed port, procedure 2, i.e., sampling source countries or netw ork hops uniformly , reduced the informa- tion quality . Relati v e to the concordance rate of the accessed port, method 2 obtained better results compared to method 1. W e conclude that the proposed methods can achie v e higher tolerance to l ocalisation attacks by reducing the sampling pack ets as a range of random number defined in procedure 1 and threshold defined in procedure 2 become small. Ho we v er , de gradation of information quality occurred. T able 7. Sampling results of pre vious w ork ( m; n ) Number of Discrepanc y , S im Mark ers 1 L (10 ; 20) 1.02 0.0694 0.833 (25 ; 35) 2.08 0.0352 0.910 (40 ; 50) 3.05 0.0140 0.949 T able 8. Sampling results of method 1 based on arri v al time and source countries ag ainst botnet A ( m; n ) 1 Number of Discrepanc y , S im Mark ers 1 L (10 ; 20) 10% 0.18 0.0621 0.742 (10 ; 20) 15% 0.62 0.0556 0.753 (25 ; 35) 10% 0.10 0.0509 0.744 (25 ; 35) 15% 0.76 0.0417 0.771 (40 ; 50) 10% 0.20 0.0466 0.743 (40 ; 50) 15% 1.82 0.0312 0.803 Countermeasur es a gainst darknet localisation attac ks... (Masaki Narita) Evaluation Warning : The document was created with Spire.PDF for Python.
1044 r ISSN: 2502-4752 T able 9. Sampling results of method 1 based on arri v al time and source countries ag ainst botnet B ( m; n ) 1 Number of Discrepanc y , S im Mark ers 1 L (10 ; 20) 10% 1.00 0.0621 0.743 (10 ; 20) 15% 1.00 0.0617 0.750 (25 ; 35) 10% 1.92 0.0419 0.743 (25 ; 35) 15% 2.24 0.0372 0.773 (40 ; 50) 10% 3.06 0.0320 0.743 (40 ; 50) 15% 3.08 0.0226 0.796 T able 10. Sampling results of method 2 based on arri v al time and TTL ag ainst botnet A ( m; n ) 2 Number of Discrepanc y , S im Mark ers 1 L (10 ; 20) 10% 0.34 0.0601 0.786 (10 ; 20) 15% 0.60 0.0556 0.822 (25 ; 35) 10% 0.32 0.0482 0.839 (25 ; 35) 15% 1.18 0.0412 0.874 (40 ; 50) 10% 0.38 0.0434 0.883 (40 ; 50) 15% 1.86 0.0327 0.912 T able 11. Sampling results of method 2 based on arri v al time and TTL ag ainst botnet B ( m; n ) 2 Number of Discrepanc y , S im Mark ers 1 L (10 ; 20) 10% 0.76 0.0656 0.789 (10 ; 20) 15% 1.16 0.0637 0.820 (25 ; 35) 10% 2.00 0.0422 0.835 (25 ; 35) 15% 2.08 0.0392 0.873 (40 ; 50) 10% 3.00 0.0302 0.885 (40 ; 50) 15% 3.04 0.0245 0.914 In our pre vious w ork, pre v enting a localisation attack w as dependent on t h e probability . As sho wn in Figure 6, spik es are further emphasised if each sensor captures all pack ets sent by attack ers based on the time selected by random numbers. This is a major problem that must be addressed. Methods 1 and 2 alle viated a problem by sampling source c o unt ries or netw ork hops uniformly in procedure 2 if sensors capture all pack ets sent by attack ers in procedure 1. As sho wn in Figures 7 and 8, the proposed methods curb mark ers if the number of hosts managed by attack ers is small and attrib utions are greatly biased. Figure 9 sho ws that our method can pre v ent mark ers as the thres hold defined in procedure 2 is lo w . If the number of hosts managed by attack ers is lar ge and attrib utions are unbiased, the proposed methods could alle viate an impact of mark ers. Figure 6. Publicised graph produced by our pre vious method under the conditions of ( m; n ) = ( 2 5 ; 35) Figure 7. Publicised graph produced by method 1 to counteract botnet A under the conditions of ( m; n ) = (25 ; 35) , threshold 1 = 15% Indonesian J Elec Eng & Comp Sci, V ol. 19, No. 2, August 2020 : 1036 1047 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 1045 Figure 8. Publicised graph produced by method 2 to counteract botnet A under the conditions of ( m; n ) = (25 ; 35) , threshold 2 = 13% Figure 9. Publicised graph produced by method 1 to counteract botnet A under the conditions of ( m; n ) = (25 ; 35) , threshold 1 = 10% 7. CONSIDERA TIONS ON THRESHOLD FLUCTU A TIONS AND VERIFICA TION OF TRADE-OFF As demonstrated by the e xperimental results, as the sampling parameters and the number of pack ets to be acquired decrease, the resistance to localisation attacks increases; ho we v er , the information quality is reduced. Con v ersely , if the number of pack ets to be acquired increases, information that is similar to the original information can be obtained. The tw o are in a trade-of f relationship. T o v erify this trade-of f relationship, we performed additional e xperiments with v arying parameters for our proposed methods. In general, similar results were obtained with methods 1 and 2, i.e., resistance to localisation attacks impro v ed as the threshold v alue decreased. By focusing on the destination port match rate, T able 12 (with a common v alue for threshold 2 ) sho ws that the match rate of the destination port fluctuates. In contrast, there is no change in the match rate of the destination in T able 13 (with a common v alue for threshold 1 ). By comparing the results in T able 14 and T able 15, the destination port match rate als o decre ases as the threshold 1 decreases sharply . From this, it is considered that the influence of the ratio of transmission source country on the matching rate of the destination port is lar ge. Note that if the method 1 is adopted, we need to configure random number width ( m; n ) as small and control threshold v alue 1 to realise resistance to localisation attacks and maintain high information quality . T able 12. Proposed method 2: Experimental results (botnet B) with only random number width (m, n) of sampling method focusing on arri v al time and TTL ( m; n ) 2 The Number of Discrepanc y , S im Mark ers 1 L (10 ; 20) 0.94 0.0617 0.791 (20 ; 30) 1.64 0.0467 0.821 (25 ; 35) 10% 1.86 0.0411 0.840 (40 ; 50) 2.84 0.0309 0.883 (50 ; 60) 3.64 0.0245 0.905 T able 13. Proposed method 1: Experimental results (botnet B) with only random number width (m, n) of sampling method focusing on arri v al time and source country ( m; n ) 1 The Number of Discrepanc y , S im Mark ers 1 L (10 ; 20) 1.12 0.0613 0.743 (20 ; 30) 1.66 0.0469 0.743 (25 ; 35) 10% 1.92 0.0419 0.743 (40 ; 50) 2.68 0.0337 0.743 (50 ; 60) 3.66 0.0275 0.743 Countermeasur es a gainst darknet localisation attac ks... (Masaki Narita) Evaluation Warning : The document was created with Spire.PDF for Python.