Anatomy of Java Vulnerabilities - NLJug 2018
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The document discusses Java vulnerabilities, illustrating how even minor bugs can lead to significant exploits affecting system availability and security. It emphasizes the importance of understanding vulnerabilities, their impacts, and proper management to mitigate risks. The presentation highlights various attack vectors, the financial scale of cybercrime, and how developers can inadvertently create security flaws.
![TrustManager[] trustAllCerts = new TrustManager[]{
new X509TrustManager() {
public X509Certificate[] getAcceptedIssuers() {
return null;
}
public void checkClientTrusted(
X509Certificate[] certs, String authType) {
}
public void checkServerTrusted(
X509Certificate[] certs, String authType) {
}
public boolean isClientTrusted( X509Certificate[] cert) {
return true;
}
public boolean isServerTrusted( X509Certificate[] cert) {
return true;
}
}}
Ever written
something
like this?
@spoole167](https://image.slidesharecdn.com/nljug14march2018anatomyjavavulnerabilities-180315181405/85/Anatomy-of-Java-Vulnerabilities-NLJug-2018-42-320.jpg)
Anatomy of Java Vulnerabilities - NLJug 2018
- 1. @spoole167 Anatomy of Java Vulnerabilities Steve Poole 15th March 2018
- 2. @spoole167 About me Steve Poole IBM Lead Engineer / Developer advocate Making Java Real Since Version 0.9 Open Source Advocate DevOps Practitioner (whatever that means!) Driving Change
- 3. @spoole167 This talk is about Java Vulnerabilities
- 4. @spoole167 How the industry manages vulnerabilities And what are attack vectors
- 5. @spoole167 Scary things and why you should care
- 6. @spoole167 And several code examples And what you should do next
- 7. @spoole167 So what is a Vulnerability?
- 8. @spoole167 Consider this two character change
- 9. @spoole167 • Fixes a bug in java.math.Double.parseDouble() • The bug causes a infinite hang when parsing an obscure value: • 2.2250738585072012e-308 • First noticed and reported in 2001 • Sat in a public bug database for 10 years • Received very little attention Interesting corner case, but not really significant… @spoole167
- 10. @spoole167 Not a corner case after all • If an attacker can make a server parse the bad value => DoS • If code parses a Double from untrusted String data, it’s vulnerable • Nearly every Java-based web service was affected • Example: • Find a HTTP header which is a double • Send HTTP requests with the header set to the bad value • Server’s worker threads are quickly tied up in infinite loops • Server cannot process any requests => DoS @spoole167
- 11. @spoole167 http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/ Large cost to everyone to produce and apply patches So many servers were brought to their knees ‘just for kicks’ Trivial to exploit Curious people everywhere Huge impact Rediscovered in 2011:
- 12. “A vulnerability is a bug which can be exploited by an attacker” @spoole167
- 13. @spoole167 Exploits are many and various • Exploits can attack your availability • Bringing your system down by making it crash • Making your system unresponsive though excessive memory / CPU / network usage • Exploits can reduce Integrity • Modification of application data • Arbitrary code execution • Exploits can breech confidentiality • Privilege elevation • Exposure of sensitive information • Exploits can use your CPU to mine bitcoin – or attack some one else..
- 14. @spoole167 Why should you care?
- 16. @spoole167 https://www.flickr.com/photos/stignygaard/ Do you think cybercriminals are lone hackers?
- 17. https://www.flickr.com/photos/bk1bennett/ Do you think cybercrime is as obvious?
- 18. Dear Winner, This is to inform you that you have been selected for a prize of a brand new 2016 Model BMW Hydrogen 7 Series Car, a Check of $500,000.00 USD and an Apple laptop from the international balloting programs held on the 27th, section of the 2016 annual award promo in the UNITED STATE OF AMERICA. Think you’re too smart to be suckered? @spoole167
- 19. @spoole167 In 2016 Cybercrime was estimated to be worth 450 Billion Dollars @spoole167 Organized Cybercrime is the most profitable type of crime In 2016 The illicit drug trade was estimated to be worth 435 Billion Dollars
- 20. @spoole167 Organized Cybercrime is the most profitable type of crime • Guess which one has the least risk to the criminal ? • Guess which is growing the fastest ? • Guess which one is the hardest to prosecute ? • Guess which one is predicted to reach 2100 Billion Dollars by 2019? • Guess which one is predicted to reach 6000 Billion Dollars by 2021? @spoole167
- 21. @spoole167 0 1000 2000 3000 4000 5000 6000 2013 2014 2015 2016 2017 2018 2019 2020 2021 Cybercrime Drug trade
- 22. @spoole167 That’s about $750 for every person on the planet Or 13% of the worlds GNP
- 24. @spoole167 I have this directory… “/Users/spoole/foo bar” with a space in the name I want to refer to it in a URL…. "file:///Users/spoole/foo%20bar"
- 25. URL u=new URL("file:///Users/spoole/foo%20bar"); File f=new File(u.getPath()); System.out.println("path="+f.getAbsolutePath()); System.out.println("exists="+f.exists());
- 26. path=/Users/spoole/foo%20bar exists=false URL u=new URL("file:///Users/spoole/foo%20bar"); File f=new File(u.getPath()); System.out.println("path="+f.getAbsolutePath()); System.out.println("exists="+f.exists());
- 27. @spoole167 Oops – forgot to decode it
- 28. URL u=new URL("file:///Users/spoole/foo%20bar"); URI uri = u.toURI(); File f=new File(uri.getPath()); System.out.println("path="+f.getAbsolutePath()); System.out.println("exists="+f.exists());
- 29. URL u=new URL("file:///Users/spoole/foo%20bar"); URI uri = u.toURI(); File f=new File(uri.getPath()); System.out.println("path="+f.getAbsolutePath()); System.out.println("exists="+f.exists()); path=/Users/spoole/foo bar exists=true
- 30. @spoole167 What would happen if someone had created a directory called ”/Users/spoole/foo%20bar” ?
- 31. @spoole167 What would happen if someone had created a directory called ”/Users/spoole/foo%20bar” ? path=/Users/spoole/foo%20bar exists=true
- 32. @spoole167 Not a big deal?
- 33. @spoole167 On Windows anyone can create a top level directory md “C:foo%20bar”
- 34. @spoole167 Still not a big deal?
- 35. @spoole167 What happens if your extensions path has an entry like “C:/Program%20Files/optional-product/extensions” And you didn’t have the product installed. You might never notice
- 36. @spoole167 Suppose the JVM didn’t decode the entry when searching for dll’s etc And suppose someone created a directory that matched “C:/Program%20Files/optional-product/extensions” Someone might be able to get your application to load sinister dlls Because of 1 line of missing code: URI uri = u.toURI();
- 37. @spoole167 Not quite a true story. But a similar vulnerability has been fixed in the JVM https://www.flickr.com/photos/koolmann/ @spoole167
- 38. @spoole167 Vulnerabilities are almost always simple there are no smoking guns Exploits are chaining together vulnerabilities https://www.flickr.com/photos/84744710@N06/
- 39. @spoole167 Developers are exploited too • Why ? • We know the inside story • We write the code • We have elevated privileges • We are over trusting • We use other peoples code and tools without inspection • we are ignorant of security matters The bad guys prey on the weak, vulnerable and ignorant
- 40. Don’t agree? The bad guys prey on the weak, vulnerable and ignorant: That’s us @spoole167
- 41. Ever googled for: “very trusting trust manager” “Getting Java to accept all certs over HTTPS” “How to Trust Any SSL Certificate” “Disable Certificate Validation in Java” @spoole167
- 42. TrustManager[] trustAllCerts = new TrustManager[]{ new X509TrustManager() { public X509Certificate[] getAcceptedIssuers() { return null; } public void checkClientTrusted( X509Certificate[] certs, String authType) { } public void checkServerTrusted( X509Certificate[] certs, String authType) { } public boolean isClientTrusted( X509Certificate[] cert) { return true; } public boolean isServerTrusted( X509Certificate[] cert) { return true; } }} Ever written something like this? @spoole167
- 43. @spoole167 We’ve all done something like that
- 44. @spoole167 We’ve all done something like that We do it all the time
- 45. @spoole167 We’ve all done something like that We do it all the time The whole world does it How bad can it be?
- 46. @spoole167 We’ve all done something like that We do it all the time The whole world does it Github search “implements TrustManager” ….
- 47. @spoole167 We’ve found 103492 code results AlwaysValidTrustManager TrustAllServersWrappingTrustManager A very friendly, accepting trust manager factory. Allows anything through. all kind of certificates are accepted and trusted. A very trusting trust manager that accepts anything // Install the all-trusting trust manager OverTrustingTrustProvider AllTrustingSecurityManagerPlugin.java AcceptingTrustManagerFactory.java AllTrustingCertHttpRequester.java
- 48. We’ve all done something like that Sometimes it even a ‘feature’ @spoole167
- 49. “A vulnerability is a bug which can be exploited by an attacker” @spoole167
- 50. “A vulnerability is a bug which can be exploited by an attacker” “A vulnerability is also a feature which can be exploited by an attacker” @spoole167
- 51. @spoole167 Vulnerabilities • Bugs and design flaws in your software and the software you use. • Everyone has them. • Researchers are looking for them all the time. •So are the bad guys https://www.flickr.com/photos/electronicfrontierfoundation/
- 52. @spoole167 The process of managing vulnerabilities
- 53. @spoole167 “Common Vulnerabilities & Exposures” • https://cve.mitre.org • The Standard place find details about ‘CVEs’ • International cyber security community effort • Common naming convention and unique references. • Allows you to know when a problem is resolved in something you are using
- 54. @spoole167 ‘CVEs’ https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=* keywords=java serialization “12” keyword=java “1692”
- 55. @spoole167 CVE-2016-2510 BeanShell (bsh) before 2.0b6, when included on the classpath by an application that uses Java serialization or XStream, allows remote attackers to execute arbitrary code via crafted serialized data, related to XThis.Handler. CVE-2016-0686 Unspecified vulnerability in Oracle Java SE 6u113, 7u99, and 8u77 and Java SE Embedded 8u77 allows remote attackers to affect confidentiality, integrity, and availability via vectors related to Serialization. CVE-2015-4805 Unspecified vulnerability in Oracle Java SE 6u101, 7u85, and 8u60, and Java SE Embedded 8u51, allows remote attackers to affect confidentiality, integrity, and availability via unknown vectors related to Serialization. keywords=java serialization (first three as of May 11th)
- 56. @spoole167 CVE-2016-0686 “Unspecified vulnerability in Oracle Java SE 6u113, 7u99, and 8u77 and Java SE Embedded 8u77 allows remote attackers to affect confidentiality, integrity, and availability via vectors related to Serialization.” That’s all you will find about this fix
- 57. Talking about the details of a fix or flaw in public is just like tweeting your credit card # and pin @spoole167 So we don’t. We give you information about the impact instead.
- 58. @spoole167 Common Vulnerability Scoring System • Base CVSS combines several aspects into a single score • Attack vector and complexity – local, remote etc. • Impact – integrity, confidentiality etc. • Privileges required? • Represented as a base score and a CVSS vector • CVSS 9.6 (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H) • Additional temporal CVSS considers aspects that may change over time • Availability of an exploit • Availability of a fix • IBM X-Force • IBM’s security research organization • Provides base and temporal CVSS scores for all published CVEs
- 59. @spoole167 Example CVSS vector • CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H • Attack Vector: N (network) • Attack Complexity: L (low) • Privileges Required: N (none) • User Interaction: R (required) • Scope: C (changed) • Confidentiality impact: H (high) • Integrity impact: H (high) • Availability impact: H (high) • Using the CVSS v3.0 calculator • Low = 0.0-3.9. Medium= 4.0-6.9 High= 7.0-8.9 Critical = 9.0-10.0 Note – assessments are based on the assumption that everyone behaves “sensibly” If you give everyone root access to a machine your mileage will differ
- 60. @spoole167 How are vulnerabilities communicated? • Oracle • CPU Advisory • Risk Matrix • IBM • Java and Product Security Bulletins • All IBM Security Bulletins are communicated on the PSIRT blog • Can subscribe to Bulletins for specific products using My Notifications • Java SDK Developer Centre
- 61. @spoole167 What if I discover a vulnerability? • Report it responsibly • Oracle or OpenJDK component (e.g. HotSpot VM, AWT, Net, Plugin) • Report it to Oracle • IBM component (e.g. J9VM, IBM ORB, IBM JCE/JSSE) • Report it to IBM • Dont • shout about it! • send a mail to an OpenJDK mailing list • post the details on a forum/blog • sell it to the bad guys • worry about apparent lack of severity – always report it
- 62. @spoole167 How are Java vulnerabilities addressed? • Ideally as quickly as possible, but it depends on • CVSS • Impending disclosure • Resources • In general: • Issues categorised internally • Fixes targeted for a future scheduled regular security release • Fixes may be deferred or brought forward if things change • Extremely urgent issues may trigger an out of cycle release
- 63. @spoole167 Vulnerability applicability • High CVSS is irrelevant if the issue does not apply to you • Java plugin flaws don’t apply to appserver deployments • JAXP issues aren’t relevant if you don’t parse untrusted XML data • Use the Oracle CPU Risk Matrix • Base CVSS scores and vectors • Consider the attack vector for the vulnerability • Oracle Applicability notes • IBM customers: if in doubt, contact IBM Support • IBM Products have detailed applicability information
- 64. If you don’t know what your code does: you don’t know if you’re vulnerable If you don’t know what your dependencies do: you don’t know if you’re vulnerable BTW: You don’t know all your dependencies @spoole167
- 66. @spoole167 Attack Vectors – Untrusted Code • Code is able to bypass or escape the SecurityManager • Affects any application which runs untrusted code under a security manager • Some server applications do this! • Flaw can be in any component on the classpath • Partial bypass • Exposure of sensitive information – e.g. system property values, heap contents • Arbitrary network connections • Full bypass • Arbitrary code execution and access to operating system • Many server deployments run as root/admin SecurityManager offers no protection against CPU DoS attacks or Infinite loops
- 67. @spoole167 Attack Vectors – Plugin / Web Start • True “client-side” issues • Affect JREs installed as the system default • Exploits can be triggered remotely, usually via a browser • Malicious applet or JNLP file • May involve platform or browser specific components • Installer/updater • Windows Registry entries • Browser callbacks • OS Shell behaviour (command line parsing) • Inappropriate privilege elevation • Applets and browser plugins are deprecated in JDK 9
- 68. @spoole167 Attack Vectors – Untrusted Data • A Java SE API mishandles a specific type of data • XML, JPG, URLs, Fonts, JARs, Strings • Issues tend to be more severe when the API is implemented natively • Maliciously-crafted data can exploit the bug • DoS – CPU/memory usage, crash • Exposure of sensitive data – arbitrary memory access • Arbitrary code execution – code injection, disabling of SecurityManager • Affects any application which handles the specific data type from untrusted sources • Examples • A server application which allows users to upload images • A server application which accepts SOAP requests • A server application with an XML-based REST API
- 69. JPEG 2000 image exploit on the OpenJPEG openjp2 version 2.1.1 A specially crafted image caused a buffer overflow in the JPEG code and overwrites memory in such a way to allow allow arbitrary code execution https://www.flickr.com/photos/mediumpanda/ https://www.flickr.com/photos/jasonahowie/
- 70. Content-Type: %{(#_='multipart/form-data'). (#_memberAccess=@ognl.OgnlContext@DEFAULT_MEMBER_ACCESS) . (@java.lang.Runtime@getRuntime().exec('curl localhost:8000'))} https://dzone.com/articles/will-it-pwn-cve-2017-5638-remote-code- execution-in Apache Struts OGNL If type contains “multipart/form-data’ try to parse it as form data This fails and as part of the building an error message the OGNL is evaluated…
- 71. @spoole167 Attack Vectors – Cryptographic Issues • Protocol flaws • Many implementations affected (Java, GSKit, OpenSSL, Browsers) • BEAST, POODLE, SLOTH, Logjam, Bar Mitzvah • Implementation flaws • Specific to Java • No fancy names! • Variable Impact • DoS • Private key exposure • Decryption of encrypted data
- 72. @spoole167 Attack Vectors – Local • Can only be exploited by a local user • Exposure of sensitive data • E.g. temp files with inappropriate permissions • Code injection • E.g. native code loaded from an unexpected location due to bad LIBPATH • May lead to a remotely exploitable vulnerability • E.g. local user plants malicious code which can be executed remotely • Usually low CVSS due to the access required
- 73. You don’t think you’re vulnerable to local attacks? @spoole167
- 76. @spoole167 Wanna Cry • Friday, 12 May 2017 • Has infected 250K computers in 150+ countries • It encrypts data and holds it for ransom • The computer owner has a limited time to pay (in bitcoin) about $500 • bitcoin owners received about 50 bitcoins ~= $85K ($3/infected machine) UK: National Health Service impacted: India: All ATMs closed Nissan: Halted all production Renault: Halted some production https://en.wikipedia.org/wiki/WannaCry_ransomware_attack Your Java server is not as secure as you think @spoole167
- 78. @spoole167 Deserialization Vulnerabilities • Abuse of the readObject() method of one or more classes • readObject() is invoked before the data is deserialized • Attackers use “gadget chains” in classes on the server’s classpath • Usually a complex set of nested objects which result in a Runtime.exec() • Costly to fix – servers may have multiple copies of the vulnerable code • Applications are vulnerable if they: • Have the vulnerable code on their classpath • Accept untrusted serialized data (this is much more common that you might think!) • Known for years, but came to prominence with problem in Apache Commons remote code execution • Many products affected – e.g. WebLogic, WebSphere, Tomcat, JBoss, Jenkins • Serialization filtering was added to the Java runtime in January 2017 • JEP 290 – Filter Incoming Serialization Data • Allows classes to be whitelisted
- 79. @spoole167 Example vulnerability – JDWP • JDWP = Java Debug Wire Protocol • Disabled by default – enabled with a command line option • JVM internals can be observed and modified remotely • No authentication required • Classes can be changed, code can be injected • Well-known online banking website • JDWP enabled on public facing servers • Presumably JDWP was enabled in development/test… • Found by a researcher after a simple port scan • Bug bounty => ££££ • Simple fix – disable JDWP!
- 81. public class HelpfulClassLoader { private Properties p=new Properties(System.getProperties()); public HelpfulClassLoader() { p.put("default", ”foo.StringHandler"); p.put("foo", "com.ibm.runtimes.demo.foo"); } public Class loadClassHelpfully(String handler) throws ClassNotFoundException { String className=p.getProperty(handler); try { return Class.forName(className); } catch (Exception e) { throw new ClassNotFoundException("could not create class for handler” +handler+" with value "+className); }}} Now I can do –Dfoo=bar on the command line (That’s helpful)
- 82. HelpfulClassLoader h=new HelpfulClassLoader(); try { Class c=h.loadClassHelpfully("default"); System.out.println("class for default="+c); } catch (ClassNotFoundException e) { e.printStackTrace(); } handler Class name default foo.StringHandler foo com.ibm.runtimes.demo.foo
- 83. HelpfulClassLoader h=new HelpfulClassLoader(); try { Class c=h.loadClassHelpfully("default"); System.out.println("class for default="+c); } catch (ClassNotFoundException e) { e.printStackTrace(); } class for default=class foo.StringHandler handler Class name default foo.StringHandler foo com.ibm.runtimes.demo.foo
- 84. handler Class name default foo.StringHandler foo com.ibm.runtimes.demo.fooHelpfulClassLoader h=new HelpfulClassLoader(); try { Class c=h.loadClassHelpfully(”foo"); System.out.println("class for foo="+c); } catch (ClassNotFoundException e) { e.printStackTrace(); }
- 85. handler Class name default foo.StringHandler foo com.ibm.runtimes.demo.foo java.lang.ClassNotFoundException: could not create class for handler foo with value com.ibm.runtimes.demo.foo at com.ibm.runtimes.demo.vulnerabilities.samples.HelpfulClassLoader.loadClassHelpfully(HelpfulClassLoader.java:23) at com.ibm.runtimes.demo.vulnerabilities.samples.HelpfulClassLoader.main(HelpfulClassLoader.java:40) HelpfulClassLoader h=new HelpfulClassLoader(); try { Class c=h.loadClassHelpfully(”foo"); System.out.println("class for foo="+c); } catch (ClassNotFoundException e) { e.printStackTrace(); }
- 86. handler Class name default foo.StringHandler foo com.ibm.runtimes.demo.fooHelpfulClassLoader h=new HelpfulClassLoader(); try { Class c=h.loadClassHelpfully(”java.ext.dirs"); } catch (ClassNotFoundException e) { e.printStackTrace(); }
- 87. handler Class name default foo.StringHandler foo com.ibm.runtimes.demo.fooHelpfulClassLoader h=new HelpfulClassLoader(); try { Class c=h.loadClassHelpfully(”java.ext.dirs"); } catch (ClassNotFoundException e) { e.printStackTrace(); } java.lang.ClassNotFoundException: could not create class for handler java.ext.dirs with value /Users/spoole/Library/Java/Extensions: /Library/Java/JavaVirtualMachines/jdk1.8.0_102.jdk/Contents/Home/jre/lib/ext: /Library/Java/Extensions:/Network/Library/Java/Extensions: /System/Library/Java/Extensions: /usr/lib/java
- 88. @spoole167 Something like this helpful code Coupled with the missing URL decoder check and the remote execution code inside Wanna Cry And your Java application is compromised. @spoole167
- 89. “A vulnerability is a bug which can be exploited by an attacker” “A vulnerability is also a feature which can be exploited by an attacker”
- 90. “A vulnerability is a bug which can be exploited by an attacker” “A vulnerability is also a feature which can be exploited by an attacker” “A vulnerability is also a developer aid which can be exploited by an attacker” @spoole167
- 91. @spoole167 Helping you to be more informed
- 93. @spoole167
- 94. @spoole167 1. Input Validation and Representation 2. API Abuse 3. Security Features 4. Time and State 5. Error Handling 6. Code Quality 7. Encapsulation * Environment The Seven Pernicious Kingdoms
- 96. Analysis Tools
- 98. Secure by Design - Security Design Principles for the Rest of Us https://www.slideshare.net/EoinWoods1/secure-by-design-security-design-principles- for-the-rest-of-us Online Guides
- 100. @spoole167 Summary
- 101. @spoole167 Reducing Risk • Keep all Java instances up to date • Use vulnerability scanning tools • Various around. From source code level to binary signature analysis. • Don’t write custom security managers • Don’t write custom crypto code • Don’t write custom XML parsers • Use modern encryption protocols and algorithms • Be very careful with: • Untrusted data , Deserialization (including RMI and JMX) • JDWP, Runtime.exec() • Native code If you are receiving data of any sort: validate it. @spoole167
- 102. @spoole167 Keeping safe: it’s in your hands Keep current. Every vulnerability fix you apply is one less way in. Compartmentalize. Separate data, code, access controls etc. Just like bulkhead doors in a ship: ensure one compromise doesn’t sink your boat. Design for intrusion. Review you levels of ‘helpfulness’ and flexibility Learn about Penetration Testing Learn about security tools & services - IBM App Scan, lgtm.com Learn about secure coding - https://cwe.mitre.org http://www.oracle.com/technetwork/java/seccodeguide-139067.html , Understand that making your development life easier makes the hackers job easier @spoole167
- 103. There are bad guys out there and your application is at risk Don’t make it worse by ignoring the problem https://www.flickr.com/photos/koolmann/ @spoole167
- 104. London 9th – 11th May, 2018 “Java application security the hard way - a workshop for the serious developer”