Detecting and preventing DNS abuse in · ›Domain names are often abused by cyber criminals Spam,...

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Detecting and preventing DNS abuse in .eu Lieven Desmet, KU Leuven – [email protected]

Transcript of Detecting and preventing DNS abuse in · ›Domain names are often abused by cyber criminals Spam,...

Page 1: Detecting and preventing DNS abuse in · ›Domain names are often abused by cyber criminals Spam, botnet C&C infrastructure, phishing, malware, … ›To avoid blacklisting, malicious

Detecting and preventing DNS abuse in .eu

Lieven Desmet, KU Leuven – [email protected]

Page 2: Detecting and preventing DNS abuse in · ›Domain names are often abused by cyber criminals Spam, botnet C&C infrastructure, phishing, malware, … ›To avoid blacklisting, malicious

Malicious use of domain names

› Domain names are often abused by cyber criminalsSpam, botnet C&C infrastructure, phishing, malware, …

› To avoid blacklisting, malicious actors often deploy a hit-and-run strategy

60% are only active for 1 day after registration [Hao et al]

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[Hao et al] “Understanding the Domain Registration Behavior of Spammers” IMC 2013

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Research hypothesis:

“Malicious actors register domains in bulk, and do so for longer periods of time.”

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The .eu trust strategy

› Delayed delegationPredict at time of registration whether a domain name will be used abusively

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Insights in malicious domain registrations

T. Vissers et al., Exploring the ecosystem of malicious domain registrations in the .eu TLD,

Research in Attacks, Intrusions, and Defenses (RAID 2017), September 2017.

https://link.eurid.eu/prediction1

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Activity of identified campaigns

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879133317151672 177 194 93 324

1624 125

1275 490 154 989 514 842 283

1291 752

1978

TOTAL MALICIOUS REGISTRATIONS:

c_20c_19c_18c_17c_16c_15c_14c_13c_12c_11c_10c_09c_08c_07c_06c_05c_04c_03c_02c_01

Apr2015

May2015

Jun2015

Jul2015

Aug2015

Sep2015

Oct2015

Nov2015

Dec2015

Jan2016

Feb2016

Mar2016

Apr2016

May2016

Jun2016

Cam

paig

ns

Registrations per day ● ● ● ●100 200 300 400

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Insight 1: Varying campaign characteristics

› Simple campaign (c_14)

› Single (fake) registrant used

throughout the campaign

• 41 days active

• 989 blacklisted registrations(= 95.37%)

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Example campaign (c_11)

› Multiple fake registrant details Combinations of

2 email accounts, 3 phone numbers, 4 street addresses

8

• 8 months active

• 1,275 blacklisted registrations(= 53.96%)

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Example of an advanced campaign (c_15)

› Registrant details:

98 fake registrants

Generated by Laravel Faker tool

› Domain names:

Consist out of 2-3 Dutch words

Dutch words are reused across

registrants

› Batches of 8, 16, 24 or 32

registrations

9

• 8+ months active

• 514 blacklisted registrations(= 26.95%)

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Insight 2: Small set of malicious actors●●●●●● ● ●● ● ●●●●●●●●●●●●● ●● ●● ●

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879133317151672 177 194 93 324

1624 125

1275 490 154 989 514 842 283

1291 752

1978

TOTAL MALICIOUS REGISTRATIONS:

c_20c_19c_18c_17c_16c_15c_14c_13c_12c_11c_10c_09c_08c_07c_06c_05c_04c_03c_02c_01

Apr2015

May2015

Jun2015

Jul2015

Aug2015

Sep2015

Oct2015

Nov2015

Dec2015

Jan2016

Feb2016

Mar2016

Apr2016

May2016

Jun2016

Cam

paig

ns

Registrations per day ● ● ● ●100 200 300 400

10At most 20 actors represent 80% of malicious registrations

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Insight 3: Top facilitators for malicious registrations

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Insight 4: Some campaigns align with regular business activity patterns (1)

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0.000

0.005

0.010

0.015

Apr 06 Apr 13 Apr 20 Apr 27

Dai

ly s

hare

of r

egis

tratio

ns

Malicious registrations All registrations

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Insight 4: Some campaigns align with regular business activity patterns (2)

13

2

4

6

8

Apr 2015 Jul 2015 Oct 2015 Jan 2016 Apr 2016

Perc

enta

ge o

f mal

iciou

s re

gist

ratio

ns

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Insight 4: Some campaigns align with regular business activity patterns (3)

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Registration-time prediction of malicious intent

J. Spooren et al., PREMADOMA: An Operational Solution for DNS Registries to Prevent Malicious Domain Registrations, Annual Computer Security Applications Conference (ACSAC 2019), December 2019.

https://link.eurid.eu/prediction4

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Pro-active detection and prevention

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New

registration

Previous registrations for whichthe results (abuse/no abuse) is known

For each new registration,the system predicts if the domainwill be used for malicious activity

Domains with malicious intent can be- Detected early- Delayed- Prevented from being registeredPrediction Model

predictor

DailyTraining

Previousregistrations

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Underlying assumptions/rationales for our predictors

› Similarity-based agglomerative clusteringDomains belonging to the same campaign have very similar registration details

› Reputation-based classificationDomains using registration facilitators with a bad reputation (e.g. email providers or registrars), are likely to be malicious as well

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Predictor 1:Reputation-based classification› Reputation features of “facilitators”

› Facilitators: Technical facilitators: registrar, name servers

Communication means: email provider and phone number

› Reputation score:Represent contribution and toxicity of facilitator to malicious registrations

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A B C

CLUSTER

BENIGN MALICIOUS NEWREGISTRATIONS:

› Agglomerative clustering of malicious samples

› Based on the similarity of registration data

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Predictor 2:Similarity-based clustering

?

?

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› Closest distance of a registration to malicious domain

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Can we differentiate between benign and malicious samples?

benignm

alicious

0.0 0.1 0.2 0.3 0.4

0

10000

20000

0100020003000

Minimum distance to a malicious instance

Nb

of re

gist

ratio

ns

Page 21: Detecting and preventing DNS abuse in · ›Domain names are often abused by cyber criminals Spam, botnet C&C infrastructure, phishing, malware, … ›To avoid blacklisting, malicious

Evaluation on historical data

› Ground truth-based evaluationRecall: 66.23%

Precision: 84.57

False positive rate: 0.30%

› Campaign-based evaluation17 out of the 20 campaigns are well predicted

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Detecting and preventing abuse in .eu: “1 picture …”

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0

2000

4000

Jul 2017 Jan 2018 Jul 2018 Jan 2019

Pred

ictio

n of

bla

cklis

ted

regi

stra

tions

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As part of the EURid’s Trust & Security program, 58,966 domains were suspended in 2018.

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Operational results

› Period: July 2017 – December 2018 (18 months)Recall: 85.51%

Precision: 72.04%

False positive rate: 2.86%

› Very big campaigns (October 2017 - March 2018)

› Incomplete ground truth

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Ground truth analysis

T. Vissers et al., Assessing the Effectiveness of Domain Blacklisting Against Malicious DNS Registrations, IEEE Workshop on Traffic Measurements for Cybersecurity (WTMC 2019),

May 2019.

https://link.eurid.eu/prediction3

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Sources of ground truth

› Around 60K domains to check per day

› Simplified view: once on a abuse list, always considered malicious

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Types of abuse recorded

› Majority of abuses are related to spam (93.68%)

› Different coverage statistics per abuse list for .eu:

Spamhaus DBL: 81.07%

SURBL multi list: 50.04%

Google Safe Browsing: 1.81%

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Registration period: Apr 2015 – May 2016

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Delay of the ground truth

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Incompleteness of the blacklists

› Failed to detect?

› Never active/malicious?

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Active DormantBlacklisted Blocked Pro-actively blockedNon-blacklisted Missed Unused

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Campaign related activity

› E.g. spam triggers multiple DNS requests:SPF, DMARC, DKIM, MX, A

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Active vs Dormant – Blacklisted vs Non-blacklisted

› 5 largest campaigns in .eu (Q1-Q2 2018)

› Based on passively-logged DNS requests (.eu TLD server)

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1. Registration strategy

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0

1000

2000

3000

Jan Feb Mar Apr May

Num

ber o

f dom

ains

Campaign A B C D E Registered

Bulk registrationB

E

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1. Registration strategy

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0

1000

2000

3000

Jan Feb Mar Apr May

Num

ber o

f dom

ains

Campaign A B C D E Registered

Continuous registrationA

C D

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2. Deployment strategy (thin line)

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0

1000

2000

3000

Jan Feb Mar Apr May

Num

ber o

f dom

ains

Campaign A B C D E Registered Deployed

Continuous deploymentA

C D

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2. Deployment strategy (thin line)

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0

1000

2000

3000

Jan Feb Mar Apr May

Num

ber o

f dom

ains

Campaign A B C D E Registered Deployed

Gradual deployment, although registered in bulk

B

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3. Domain blacklisting (dotted line)

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0

1000

2000

3000

Jan Feb Mar Apr May

Num

ber o

f dom

ains

Campaign A B C D E Registered Blacklisted Deployed

Reactive blacklistingA

C D

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3. Domain blacklisting (dotted line)

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0

1000

2000

3000

Jan Feb Mar Apr May

Num

ber o

f dom

ains

Campaign A B C D E Registered Blacklisted Deployed

Blacklisting in batch

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3. Domain blacklisting (dotted line)

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0

1000

2000

3000

Jan Feb Mar Apr May

Num

ber o

f dom

ains

Campaign A B C D E Registered Blacklisted Deployed

Pro-active blacklisting

B E

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Key takeaways

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Page 40: Detecting and preventing DNS abuse in · ›Domain names are often abused by cyber criminals Spam, botnet C&C infrastructure, phishing, malware, … ›To avoid blacklisting, malicious

Rather small set of bad actors

› Up to 20 campaigns are responsible for 80% of malicious

registrations

› Top facilitators:About half of the malicious registrations via 1 registrar

1 public email provider are malicious with a high toxicity

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Registration-time detection and prevention

› Two prediction models predict at registration-time the malicious intent

› Captures the majority of malicious domain registrations

› Incompleteness of ground truth makes analysis hard

› Interesting to see how this will further impact the security landscape

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Page 42: Detecting and preventing DNS abuse in · ›Domain names are often abused by cyber criminals Spam, botnet C&C infrastructure, phishing, malware, … ›To avoid blacklisting, malicious

Attackers vs Defenders

› Ground truth is (somewhat) trickyBias towards spamDelay in labeling“Incompleteness”

› 2 different ecosystems: abusive registrationabusive activity

› Interesting to see how it will further impact the abuse landscape

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Page 43: Detecting and preventing DNS abuse in · ›Domain names are often abused by cyber criminals Spam, botnet C&C infrastructure, phishing, malware, … ›To avoid blacklisting, malicious

Interested in more? Some reading material…

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https://link.eurid.eu/prediction1 https://link.eurid.eu/prediction2 https://link.eurid.eu/prediction3 https://link.eurid.eu/prediction4

https://link.eurid.eu/prediction[1-4]

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Detecting and preventing DNS abuse in .eu

Lieven Desmet, KU Leuven – [email protected]