1. Deserialize My Shorts
Or How I Learned to Start Worrying and Hate
Java Object Deserialization
Chris Frohoff (@frohoff)
Gabriel Lawrence (@gebl) (in spirit)

2. 2
@gebl spreading The Good Word abroad
OWASP Cork, Ireland Chapter Meeting 2016/3/14

3. 3
snapshots one or more “live”, in-memory objects into a flat, serial stream of data that can be
stored or transmitted for reconstitution and use by a different process or the same process at
some point
Formats
− Binary: Java Serialization, Ruby Marshal, Protobuf, Thrift, Avro, MS-NRBF, Android Binder/Parcel, IIOP
− Hybrid/Other: PHP Serialization, Python pickle, Binary XML/JSON
− Readable: XML, JSON, YAML
Platform/Formats may have multiple implementations and/or sub-formats
Serializing Objects
a.k.a. “marshaling”, “pickling”, “freezing”, ”flattening”

4. 4
Remote/Interprocess Communication (RPC/IPC)
− Communicating data to different system/process
− Wire protocols, web services, message brokers
Caching/Persistence
− Communicating data to process’ future self
− Databases, cache servers, file systems
Tokens
− Communicating data to different system/process and back
− HTTP cookies, HTML form parameters, API auth tokens
Purposes and Mediums
Why and where

5. 5
Crash Course:
Java (de)serialization

6. 6
java.io.ObjectOutputStream java.io.ObjectInputStream
public void writeObject(Object) public Object readObject()
public void writeUTF(String) public String readUTF()
public void writeInt(int) public int readInt()
public void writeFloat(float) public float readFloat()
public void writeBoolean(boolean) public boolean readBoolean()
public void writeByte(byte) public byte readByte()
… …
Java Serialization API
readObject() and writeObject() are open-ended/polymorphic* *yes, that is scary

7. 7
Stream starts with magic & version:
− ObjectStreamConstants.STREAM_MAGIC (short, 0xACED);
− ObjectStreamConstants.STREAM_VERSION (short, 0x0005);
Polymorphic values’ serialized form prefixed with “type code”
− ObjectStreamConstants.TC_*: 0x70-0x7E
− TC_NULL=0x70, TC_REFERENCE=0x71, TC_CLASSDESC=0x72, TC_OBJECT=0x73, TC_STRING=0x74,
TC_ARRAY=0x75, TC_CLASS=0x76, TC_LONGSTRING=0x7C, TC_PROXYCLASSDESC=0x7D,
TC_ENUM=0x7E
String (UTF-8) serialized form:
− String length (int), String bytes*
Boolean serialized form:
− value (byte, 1=True, 0=False)
Java Serialized Form
Uncustomized, default, simple (de)serialization

8. 8
Java Serialized Form
Uncustomized, default, simple (de)serialization
Object serialized form:
− TC_OBJECT (byte, 0x73)
− Class Description (or ref)
− TC_CLASSDESC (byte, 0x72)
− Class Name (String)
− Serial Version UID (long)
− Field Descriptions*
− Field Type Code (byte)
− Field Name (String)
− Field Type (String, for non-primitive)
− Field values*
− [Primitive serialized form] | [Object serialized form] | ref
− Causes recursive calls to writeObject()/readObject() or read*()/write*()
• Refs: Later representations of
same object substituted with
incrementing “handles” to save
space and preserve referential
relationships
• TC_REFERENCE (byte, 0x71)
• Handle number (int)
• > 0x7e0000
• Field Type Codes:
'B'=byte, 'C'=char, 'D'=double,
'F'=float, 'I'=int, 'J'=long,
'L'=class/interface, 'S'=short,
'Z'=boolean, '['=array,

9. 9
Must implement java.io.Serializable (or java.io.Externalizable) interface
− Including all nested values
Serializable classes must have access to no-arg ctor of first non-Serializable superclass
− Uses bytecode magic to circumvent normal instantiation requirements (MagicAccessorImpl)
Skips fields marked with “transient” keyword
Serial Version UIDs in serialized form and target deserialized class must match
− By default implicitly generated based on class structure
− Can be explicitly defined in class if responsible for own serialized for compatibility
Supports java.lang.reflect.Proxy instances 
− Runtime generated class with interfaces implemented and java.lang.reflect.InvocationHandler
− Serialized form includes (Serializable) InvocationHandler instance and interfaces
Java Serialization Caveats

10. 10
Java Serialization Format
0000000: aced 0005 7372 000a 536f 6d65 4f62 6a65 ....sr..SomeObje
0000010: 6374 6fd1 f104 c2d9 8525 0200 0249 000a cto......%...I..
0000020: 536f 6d65 4e75 6d62 6572 4c00 0a53 6f6d SomeNumberL..Som
0000030: 6553 7472 696e 6774 0012 4c6a 6176 612f eStringt..Ljava/
0000040: 6c61 6e67 2f53 7472 696e 673b 7870 0000 lang/String;xp..
0000050: 0001 7400 0548 656c 6c6f ..t..Hello

11. 11
Java Serialization Format
0000000: aced 0005 7372 000a 536f 6d65 4f62 6a65 ....sr..SomeObje
0000010: 6374 6fd1 f104 c2d9 8525 0200 0249 000a cto......%...I..
0000020: 536f 6d65 4e75 6d62 6572 4c00 0a53 6f6d SomeNumberL..Som
0000030: 6553 7472 696e 6774 0012 4c6a 6176 612f eStringt..Ljava/
0000040: 6c61 6e67 2f53 7472 696e 673b 7870 0000 lang/String;xp..
0000050: 0001 7400 0548 656c 6c6f ..t..Hello
final static short STREAM_MAGIC = (short)0xaced;
final static short STREAM_VERSION = 5;

12. 12
Java Serialization Format
final static byte TC_OBJECT = (byte)0x73;
0000000: aced 0005 7372 000a 536f 6d65 4f62 6a65 ....sr..SomeObje
0000010: 6374 6fd1 f104 c2d9 8525 0200 0249 000a cto......%...I..
0000020: 536f 6d65 4e75 6d62 6572 4c00 0a53 6f6d SomeNumberL..Som
0000030: 6553 7472 696e 6774 0012 4c6a 6176 612f eStringt..Ljava/
0000040: 6c61 6e67 2f53 7472 696e 673b 7870 0000 lang/String;xp..
0000050: 0001 7400 0548 656c 6c6f ..t..Hello

13. 13
Java Serialization Format
final static byte TC_CLASSDESC = (byte)0x72;
0000000: aced 0005 7372 000a 536f 6d65 4f62 6a65 ....sr..SomeObje
0000010: 6374 6fd1 f104 c2d9 8525 0200 0249 000a cto......%...I..
0000020: 536f 6d65 4e75 6d62 6572 4c00 0a53 6f6d SomeNumberL..Som
0000030: 6553 7472 696e 6774 0012 4c6a 6176 612f eStringt..Ljava/
0000040: 6c61 6e67 2f53 7472 696e 673b 7870 0000 lang/String;xp..
0000050: 0001 7400 0548 656c 6c6f ..t..Hello

14. 14
Java Serialization Format
className:
(utf)
0000000: aced 0005 7372 000a 536f 6d65 4f62 6a65 ....sr..SomeObje
0000010: 6374 6fd1 f104 c2d9 8525 0200 0249 000a cto......%...I..
0000020: 536f 6d65 4e75 6d62 6572 4c00 0a53 6f6d SomeNumberL..Som
0000030: 6553 7472 696e 6774 0012 4c6a 6176 612f eStringt..Ljava/
0000040: 6c61 6e67 2f53 7472 696e 673b 7870 0000 lang/String;xp..
0000050: 0001 7400 0548 656c 6c6f ..t..Hello

15. 15
Java Serialization Format
primitiveDesc:
prim_typecode fieldName
0000000: aced 0005 7372 000a 536f 6d65 4f62 6a65 ....sr..SomeObje
0000010: 6374 6fd1 f104 c2d9 8525 0200 0249 000a cto......%...I..
0000020: 536f 6d65 4e75 6d62 6572 4c00 0a53 6f6d SomeNumberL..Som
0000030: 6553 7472 696e 6774 0012 4c6a 6176 612f eStringt..Ljava/
0000040: 6c61 6e67 2f53 7472 696e 673b 7870 0000 lang/String;xp..
0000050: 0001 7400 0548 656c 6c6f ..t..Hello

16. 16
Java Serialization Format
objectDesc:
obj_typecode fieldName className1
0000000: aced 0005 7372 000a 536f 6d65 4f62 6a65 ....sr..SomeObje
0000010: 6374 6fd1 f104 c2d9 8525 0200 0249 000a cto......%...I..
0000020: 536f 6d65 4e75 6d62 6572 4c00 0a53 6f6d SomeNumberL..Som
0000030: 6553 7472 696e 6774 0012 4c6a 6176 612f eStringt..Ljava/
0000040: 6c61 6e67 2f53 7472 696e 673b 7870 0000 lang/String;xp..
0000050: 0001 7400 0548 656c 6c6f ..t..Hello

17. 17
Java Serialization Format
Value for SomeNumber
0000000: aced 0005 7372 000a 536f 6d65 4f62 6a65 ....sr..SomeObje
0000010: 6374 6fd1 f104 c2d9 8525 0200 0249 000a cto......%...I..
0000020: 536f 6d65 4e75 6d62 6572 4c00 0a53 6f6d SomeNumberL..Som
0000030: 6553 7472 696e 6774 0012 4c6a 6176 612f eStringt..Ljava/
0000040: 6c61 6e67 2f53 7472 696e 673b 7870 0000 lang/String;xp..
0000050: 0001 7400 0548 656c 6c6f ..t..Hello

18. 18
Java Serialization Format
final static byte TC_STRING = (byte)0x74;
TC_STRING newHandle (utf)
0000000: aced 0005 7372 000a 536f 6d65 4f62 6a65 ....sr..SomeObje
0000010: 6374 6fd1 f104 c2d9 8525 0200 0249 000a cto......%...I..
0000020: 536f 6d65 4e75 6d62 6572 4c00 0a53 6f6d SomeNumberL..Som
0000030: 6553 7472 696e 6774 0012 4c6a 6176 612f eStringt..Ljava/
0000040: 6c61 6e67 2f53 7472 696e 673b 7870 0000 lang/String;xp..
0000050: 0001 7400 0548 656c 6c6f ..t..Hello

19. 19
java.io.Serializable
− void writeObject(ObjectOutputStream): customize object serialization
− Use ObjectOutputStream write*(), defaultWriteObject(), and/or putFields()
− void readObject(ObjectInputStream): customize object deserialization
− Use ObjectInputStream read*(), defaultReadObject(), and/or readFields()
− Object writeReplace(): provide stand-in object for serialization
− Object readResolve(): provide stand-in object for deserialization
java.io.Externalizable: fully customized and explicit serialization
− void readExternal(ObjectInput): manually read fields from stream
− void writeExternal(ObjectOutput): manually write fields to stream
Customizing Java Serialization
Implement interfaces/methods on class to be (de)serialized

20. 20
Java Serialization Stream Header
− 0xACED 0x0005 …
− “rO0AB…”
GZIP Header
− 0x1F8B 0x0800 …
− “H4sIA…”
Anywhere you see a fully qualified class name
− org.apache.commons.collections.functors.InvokerTransformer
Some sequences to recognize

21. 21

22. 22
Code reuse attack (a la ROP)
Uses “gadget” classes already in scope of application
Create chain of instances and method invocations
− Start with “kick-off” gadget that executes during or after deserialization
− End in “sink” gadget that executes arbitrary code/commands
− Use other “helper” gadgets to chain start gadget execution to end gadget
Serialize chain and send to vulnerable deserialization in application
Chain executed in application during/after deserialization
Profit
Property-Oriented Programming / Object Injection
Earliest POP research we
found was by Stefan Esser
(@i0n1c), “Utilizing Code
Reuse/ROP in PHP
Application Exploits"

23. 23
Rube-Goldberg-esque
Gadget chains are generally carrier-medium, application, and OS/platform agnostic
− Relies only on code available to application
− Not necessarily code used by application
Gadget Classes
− Target common libraries/frameworks. Library sprawl FTW.
− “Proxy” gadgets versatile
− Deserialization hook methods for self-execution
Gadget hunting and chain construction is an art
− Can be frustrating and tedious
− Rich IDEs help, but custom tools are better
− https://github.com/frohoff/inspector-gadget (out of scope for talk)
Property-Oriented Programming / Object Injection

24. 24
A Simple Java Gadget Chain
ObjectInputStream.readObject()
“calc.exe”

25. 25
Time-Lapse of Deserialization
ObjectInputStream.readObject() called
ObjectInputStream
readObject()
defaultReadObject()

26. 26
Time-Lapse of Deserialization
CacheManager instance allocated
CacheManager
ObjectInputStream
readObject()
readObject()
defaultReadObject()

27. 27
Time-Lapse of Deserialization
CacheManager.readObject() called
CacheManager
ObjectInputStream
readObject()
readObject()
defaultReadObject()

28. 28
Time-Lapse of Deserialization
ObjectInputStream.defaultReadObject() called
CacheManager
ObjectInputStream
readObject()
readObject()
defaultReadObject()

29. 29
Time-Lapse of Deserialization
CommandTask instance allocated and referenced by CacheManager.initHook field
CacheManager
ObjectInputStream
readObject()
readObject()
defaultReadObject()
CommandTask
run()

30. 30
Time-Lapse of Deserialization
CommandTask.run() called
CacheManager
ObjectInputStream
readObject()
readObject()
defaultReadObject()
CommandTask
run()

31. 31
Time-Lapse of Deserialization
Runtime.exec() called
CacheManager
ObjectInputStream
readObject()
readObject()
defaultReadObject()
CommandTask
run()
Runtime
exec()
“calc.exe”

32. 32
Time-Lapse of Deserialization
Target program run
CacheManager
ObjectInputStream
readObject()
readObject()
defaultReadObject()
CommandTask
run()
Runtime
exec()
“calc.exe”

33. 33
Target java.lang.Runtime.exec(String cmd)
Uses gadgets in JDK and Apache Commons-Collections library
Self-executing during deserialization
− Executes before object returned to caller
A Java + Commons-Collections Gadget Chain
Similar POP techniques previously applied to
Java Serialization by Wouter Coekaerts
(@WouterCoekaerts) and implemented by
Alvaro Muñoz (@pwntester)

34. 34
Call Chain

35. 35
Gadget Chain Construction Code and Call Tree

36. 36
Demos

37. 37
Contains multiple gadget chain payloads and a few exploits
Create payload to execute calc.exe using CommonsCollections1 chain:
$ java -jar ysoserial-0.0.1-all.jar CommonsCollections1 calc.exe | xxd | head -3
0000000: aced 0005 7372 0032 7375 6e2e 7265 666c ....sr.2sun.refl
0000010: 6563 742e 616e 6e6f 7461 7469 6f6e 2e41 ect.annotation.A
0000020: 6e6e 6f74 6174 696f 6e49 6e76 6f63 6174 nnotationInvocat
$ java -jar ysoserial-0.0.1-all.jar CommonsCollections1 calc.exe > payload.bin
$ cat payload.bin | nc somehost 5555
Send exploit payload to RMI Registry listener:
$ java -cp ysoserial-0.0.1-all.jar ysoserial.RMIRegistryExploit myhost 1099 CommonsCollections1 calc.exe
ysoserial
A proof-of-concept tool for generating payloads that exploit unsafe Java object deserialization

38. 38
Code Execution via Java Serializable
JSF (MyFaces) ViewState form parameters deserialized

39. 39

40. 40
RMIRegistry

41. 41

42. 42
Imperfect Mitigations
Cover in more detail later to include new information
− Look-ahead deserialization with custom ObjectInputStream subclass
− Apply SecurityManager only during deserialization

43. 43
This is not a
new problem

44. 44
This is not a
language problem

45. 45
This is not a
format problem

46. 46
We have
trust issues

47. 47
We have
trust issues.

48. 48
Other languages/platforms
− PHP unserialize()
− Python pickle
− Ruby/Rails deserialization fiasco (YAML, XML, JSON, Marshal)
− Recent stuff: “Instagram’s Million Dollar Bug”
Java
− JSF EL Injection
− Recent stuff: “RCE in Oracle NetBeans Opensource Plugins”, “Reliable OS Shell with EL Injection”
− Commons FileUpload
− XMLDecoder/Xstream/Kryo
− Recent stuff: “Serialization Must Die”
− Recent Serializable: SerialDOS
Only covering Remote Code Execution via Java Serializable/Externalizable API today
− Original AppSecCali 2015 “Marshalling Pickles” talk covers some of the others
Out-of-scope related must-see/read stuff
Google or see references

49. 49

50. 50
2011/9/9 — Spring Vulnerabilities
Wouter Coekarts (@WouterCoekaerts)

51. 51
2011/9 — 2013/3 (18 months)

52. 52
2013/03/05 — IBM Cognos BI RCE
Pierre Ernst

53. 53
? ?: Many JSF impls without encryption/signing enabled
2013/03/15 @e_rnst: IBM Cognos BI CVE-2012-4858
Timeline of Java Serializable Pwnage
Vulnerable (or Likely) Products/Projects Gadgets/Chains
2011/9/9 Wouter Coekaerts: Spring AOP
* very much not to scale

54. 54
? ?: Many JSF impls without encryption/signing enabled
2013/03/15 @e_rnst: IBM Cognos BI CVE-2012-4858
Timeline of Java Serializable Pwnage
Vulnerable (or Likely) Products/Projects Gadgets/Chains
2011/9/9 Wouter Coekaerts: Spring AOP
* very much not to scale

55. 55
2013/3 — 2013/12 (9 months)

56. 56
2013/12/16 — Deserialization Spring RCE
Alvaro Muñoz (@pwntester)

57. 57
2013/12 — 2015/1 (14 months)

58. 58
2015/1/28 — Marshalling Pickles, ysoserial
Gabe Lawrence (@gebl) and Chris Frohoff (@frohoff) — AppSec California 2015

59. 59
2015/1/28 — Marshalling Pickles, ysoserial
Gabe Lawrence (@gebl) and Chris Frohoff (@frohoff) — AppSec California 2015

60. 60
? ?: Many JSF impls without encryption/signing enabled
2013/03/15 @e_rnst: IBM Cognos BI CVE-2012-4858
Timeline of Java Serializable Pwnage
Vulnerable (or Likely) Products/Projects Gadgets/Chains
2011/9/9 Wouter Coekaerts: Spring AOP
2015/1/28 @frohoff: Commons Collections, Groovy, Spring Beans/Core
* very much not to scale

61. 61
? ?: Many JSF impls without encryption/signing enabled
2013/03/15 @e_rnst: IBM Cognos BI CVE-2012-4858
Timeline of Java Serializable Pwnage
Vulnerable (or Likely) Products/Projects Gadgets/Chains
2011/9/9 Wouter Coekaerts: Spring AOP
2015/1/28 @frohoff: Commons Collections, Groovy, Spring Beans/Core
* very much not to scale

62. 62
2015/1 — 2015/10 (9 months)

63. 63
2015/1 — 2015/10 (9 months)

64. 64
2015/10/28 — Exploiting Deserialization Vulnerabilities in Java
Matthias Kaiser (@matthias_kaiser) — HackPra WS 2015

65. 65
2015/10/28 — Exploiting Deserialization Vulnerabilities in Java
Matthias Kaiser (@matthias_kaiser) — HackPra WS 2015
Hey, that’s us!

66. 66
2015/10/28 — Exploiting Deserialization Vulnerabilities in Java
Matthias Kaiser (@matthias_kaiser) — HackPra WS 2015
Hey, that’s us!

67. 67
2015/11/6 — What Do WebLogic, WebSphere, …
Stephen Breen (@breenmachine)
My Birthday

68. 68
2015/11/6-10 — Social Media Kills My Phone Battery
Misunderstanding and misinformation abound

69. 69
2015/11/8-16 — Evasive Maneuvers by Dev Community
Innovative Solutions and (Some) Sensible Responses

70. 70
? ?: Many JSF impls without encryption/signing enabled
2013/03/15 @e_rnst: IBM Cognos BI CVE-2012-4858
2015/10/27 @matthias_kaiser: Atlassian Bamboo CVE-2015-8360
2015/11/4 @mwulftange and @matthias_kaiser: Commvault Edge Server CVE-2015-7253
2015/11/6 @matthias_kaiser: Oracle WebLogic CVE-2015-4852
2015/11/6 @breenmachine: JBoss AS CVE-2015-7501, WebSphere CVE-2015-7450, Jenkins CVE-2015-8103, OpenNMS
2015/11/9 Joel Bernstein: Apache SOLR (SOLR-8262)
2015/11/12 Andrew Purtell: Apache HBase (HBASE-14799)
2015/11/13 @matthias_kaiser and @mwulftange: Symantec Endpoint Protection Manager CVE-2015-6555
2015/11/17 n/a: Unify OpenScape (various) CVE-2015-8237, CVE-2015-8238
2015/12/4 n/a: Apache OpenJPA, Commons JCS
2015/12/9 @pwntester, @matthias_kaiser, @cschneider4711: ActiveMQ CVE-2015-5254
2015/12/9 n/a: Cisco (various) CVE-2015-6420
2015/12/16 cpnrodzc7: TomEE CVE-2015-8581
2015/12/17 Sim Yih Tsern: Apache Camel CVE-2015-5348
2015/12/18 n/a: VMWare vCenter/vRealize (various) CVE-2015-6934
2015/12/27 n/a: Apache Batchee, Apache OpenWebBeans
2015/12/30 n/a: McAfee ePolicy Orchestrator CVE-2015-8765
Timeline of Java Serializable Pwnage
Vulnerable (or Likely) Products/Projects Gadgets/Chains
2011/9/9 Wouter Coekaerts: Spring AOP
2015/1/28 @frohoff: Commons Collections, Groovy, Spring Beans/Core
* very much not to scale

71. 71
? ?: Many JSF impls without encryption/signing enabled
2013/03/15 @e_rnst: IBM Cognos BI CVE-2012-4858
2015/10/27 @matthias_kaiser: Atlassian Bamboo CVE-2015-8360
2015/11/4 @mwulftange and @matthias_kaiser: Commvault Edge Server CVE-2015-7253
2015/11/6 @matthias_kaiser: Oracle WebLogic CVE-2015-4852
2015/11/6 @breenmachine: JBoss AS CVE-2015-7501, WebSphere CVE-2015-7450, Jenkins CVE-2015-8103, OpenNMS
2015/11/9 Joel Bernstein: Apache SOLR (SOLR-8262)
2015/11/12 Andrew Purtell: Apache HBase (HBASE-14799)
2015/11/13 @matthias_kaiser and @mwulftange: Symantec Endpoint Protection Manager CVE-2015-6555
2015/11/17 n/a: Unify OpenScape (various) CVE-2015-8237, CVE-2015-8238
2015/12/4 n/a: Apache OpenJPA, Commons JCS
2015/12/9 @pwntester, @matthias_kaiser, @cschneider4711: ActiveMQ CVE-2015-5254
2015/12/9 n/a: Cisco (various) CVE-2015-6420
2015/12/16 cpnrodzc7: TomEE CVE-2015-8581
2015/12/17 Sim Yih Tsern: Apache Camel CVE-2015-5348
2015/12/18 n/a: VMWare vCenter/vRealize (various) CVE-2015-6934
2015/12/27 n/a: Apache Batchee, Apache OpenWebBeans
2015/12/30 n/a: McAfee ePolicy Orchestrator CVE-2015-8765
Timeline of Java Serializable Pwnage
Vulnerable (or Likely) Products/Projects Gadgets/Chains
2011/9/9 Wouter Coekaerts: Spring AOP
2015/1/28 @frohoff: Commons Collections, Groovy, Spring Beans/Core
* very much not to scale

72. 72
2016/1/21-22 — JNDI/JRMP Remote Loading Gadget
@zerothoughts

73. 73
2016/1/25 — PayPal Remote Code Execution
Michael Stepankin and Mark Litchfield

74. 74
2016/1/26-2/24 — JDK <7u21, Beanutils Gadget Chains
Chris Frohoff (@frohoff)

75. 75
2016/2/24 — serianalyzer, Gadgets, Clients, etc.
Moritz Bechler (@mbechler)

76. 76
2016/3/4 — Serial Killer & The Perils of Java Deser.
Alvaro Muñoz (@pwntester) and Christian Schneider (@cschneider4711) — RSAC 2016

77. 77
2016/3/4 — Serial Killer & The Perils of Java Deser.
Alvaro Muñoz (@pwntester) and Christian Schneider (@cschneider4711) — RSAC 2016

78. 78
? ?: Many JSF impls without encryption/signing enabled
2013/03/15 @e_rnst: IBM Cognos BI CVE-2012-4858
2015/10/27 @matthias_kaiser: Atlassian Bamboo CVE-2015-8360
2015/11/4 @mwulftange and @matthias_kaiser: Commvault Edge Server CVE-2015-7253
2015/11/6 @matthias_kaiser: Oracle WebLogic CVE-2015-4852
2015/11/6 @breenmachine: JBoss AS CVE-2015-7501, WebSphere CVE-2015-7450, Jenkins CVE-2015-8103, OpenNMS
2015/11/9 Joel Bernstein: Apache SOLR (SOLR-8262)
2015/11/12 Andrew Purtell: Apache HBase (HBASE-14799)
2015/11/13 @matthias_kaiser and @mwulftange: Symantec Endpoint Protection Manager CVE-2015-6555
2015/11/17 n/a: Unify OpenScape (various) CVE-2015-8237, CVE-2015-8238
2015/12/4 n/a: Apache OpenJPA, Commons JCS
2015/12/9 @pwntester, @matthias_kaiser, @cschneider4711: ActiveMQ CVE-2015-5254
2015/12/9 n/a: Cisco (various) CVE-2015-6420
2015/12/16 cpnrodzc7: TomEE CVE-2015-8581
2015/12/17 Sim Yih Tsern: Apache Camel CVE-2015-5348
2015/12/18 n/a: VMWare vCenter/vRealize (various) CVE-2015-6934
2015/12/27 n/a: Apache Batchee, Apache OpenWebBeans
2015/12/30 n/a: McAfee ePolicy Orchestrator CVE-2015-8765
2016/1/25 Michael Stepankin and Mark Litchfield: PayPal
2016/2/9 n/a: Adobe Experience Manager CVE-2016-0958
2016/2/24 @mbechler: Jenkins CVE-2016-0788
2016/3/16 n/a: TomEE (#2) CVE-2016-0779
Timeline of Java Serializable Pwnage
Vulnerable (or Likely) Products/Projects Gadgets/Chains
2011/9/9 Wouter Coekaerts: Spring AOP
2015/1/28 @frohoff: Commons Collections, Groovy, Spring Beans/Core
2016/1/22 @zerothoughts: Spring-TX
2016/1/26 @frohoff: JDK 7u21, variation on Commons Collections
2016/2/24 @frohoff: Beanutils
2016/2/29 @mbechler: Hibernate, MyFaces, C3P0, net.sf.json, ROME, variation on Spring, JRMPClient,
JRMPListener
2016/3/4 @pwntester and @cschneider4711: Beanshell, Jython, lots of bypasses
2016/3/9 @matthias_kaiser: variation on Commons Collections
* very much not to scale

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? ?: Many JSF impls without encryption/signing enabled
2013/03/15 @e_rnst: IBM Cognos BI CVE-2012-4858
2015/10/27 @matthias_kaiser: Atlassian Bamboo CVE-2015-8360
2015/11/4 @mwulftange and @matthias_kaiser: Commvault Edge Server CVE-2015-7253
2015/11/6 @matthias_kaiser: Oracle WebLogic CVE-2015-4852
2015/11/6 @breenmachine: JBoss AS CVE-2015-7501, WebSphere CVE-2015-7450, Jenkins CVE-2015-8103, OpenNMS
2015/11/9 Joel Bernstein: Apache SOLR (SOLR-8262)
2015/11/12 Andrew Purtell: Apache HBase (HBASE-14799)
2015/11/13 @matthias_kaiser and @mwulftange: Symantec Endpoint Protection Manager CVE-2015-6555
2015/11/17 n/a: Unify OpenScape (various) CVE-2015-8237, CVE-2015-8238
2015/12/4 n/a: Apache OpenJPA, Commons JCS
2015/12/9 @pwntester, @matthias_kaiser, @cschneider4711: ActiveMQ CVE-2015-5254
2015/12/9 n/a: Cisco (various) CVE-2015-6420
2015/12/16 cpnrodzc7: TomEE CVE-2015-8581
2015/12/17 Sim Yih Tsern: Apache Camel CVE-2015-5348
2015/12/18 n/a: VMWare vCenter/vRealize (various) CVE-2015-6934
2015/12/27 n/a: Apache Batchee, Apache OpenWebBeans
2015/12/30 n/a: McAfee ePolicy Orchestrator CVE-2015-8765
2016/1/25 Michael Stepankin and Mark Litchfield: PayPal
2016/2/9 n/a: Adobe Experience Manager CVE-2016-0958
2016/2/24 @mbechler: Jenkins CVE-2016-0788
2016/3/16 n/a: TomEE (#2) CVE-2016-0779
Timeline of Java Serializable Pwnage
Vulnerable (or Likely) Products/Projects Gadgets/Chains
2011/9/9 Wouter Coekaerts: Spring AOP
2015/1/28 @frohoff: Commons Collections, Groovy, Spring Beans/Core
2016/1/22 @zerothoughts: Spring-TX
2016/1/26 @frohoff: JDK 7u21, variation on Commons Collections
2016/2/24 @frohoff: Beanutils
2016/2/29 @mbechler: Hibernate, MyFaces, C3P0, net.sf.json, ROME, variation on Spring, JRMPClient,
JRMPListener
2016/3/4 @pwntester and @cschneider4711: Beanshell, Jython, lots of bypasses
2016/3/9 @matthias_kaiser: variation on Commons Collections
* very much not to scale

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* very much not to scale

81. 81
* very much not to scale

82. 82
* very much not to scale

83. 83
Recent — Qualcomm Red Team Exercise
A colleague tried something new
Performed some new targeted scanning on internal network
Scripted ysoserial against various listeners
− Attempted multiple payload types
− Executed DNS lookup (logged at DNS server) with name of payload type
Results
− Discovered undisclosed vulnerabilities in 6 products (i.e. 0days)

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Recent — Deser Vulnerability Reported to Qualcomm

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$ java -jar target/ysoserial-0.0.5-SNAPSHOT-all.jar
Y SO SERIAL?
Usage: java -jar ysoserial-[version]-all.jar [payload type] '[command to execute]'
Available payload types:
BeanShell1
C3P0
CommonsBeanutils1
CommonsCollections1
CommonsCollections2
CommonsCollections3
CommonsCollections4
CommonsCollections5
FileUpload1
Groovy1
Hibernate1
Hibernate2
JRMPClient
JRMPListener
JSON1
Jdk7u21
Jython1
Myfaces1
Myfaces2
ROME
Spring1
Spring2
Recent — ysoserial dev activity picking up

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Recent — Good Guy Glenn
Glenn Lewis (@gmlewis)

87. 87
Mitigation

88. 88
Fundamental vulnerability is in doing unsafe deserialization, not in having gadgets available
More will be always found
Transitive dependencies cause library sprawl
Cross-library gadget chains
Auto-detection difficult
Gadget Whack-a-Mole
DO NOT rely on this!

89. 89
Fundamental vulnerability
is in doing unsafe
deserialization

90. 90
Fundamental vulnerability
is in doing unsafe
deserialization

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Avoid open-ended (de)serialization when possible
− If the serialization includes a class name, it’s probably bad
− ObjectInputStream.readObject() is not safe
− Lots of non-open-ended JVM serialization frameworks available
− https://github.com/eishay/jvm-serializers/wiki
Simple format and/or data types
− Strings, Numbers, Arrays, Maps, etc.
− Manually serialize complex objects
Keep session state on the server when possible
− Beware of lateral attacks! (memcached, redis, database, etc.)
Abstenence
Avoid magic

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Whitelist/Blacklist classes
− Use subclass of ObjectInputStream0
− override resolveClass() to allow/disallow classes
− http://www.ibm.com/developerworks/library/se-lookahead/
− Blacklisting ≈ Gadget whack-a-mole
− Difficult without robust library support
− Runtime Agents can help
− Strip Serilaizable/Externalizable interfaces from classes
− Instrument native ObjectInputStream.resolveClass()
− Subclass circumventable by “bypass gadgets”
Restrict Deserialization
Use with Caution. This is a band-aid.

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Encryption != Authentication
− See JSF Padding Oracle attacks
Authenticate channels
− TLS Client Certs, SASL, DB/Cache/Broker credentials
Authenticate content
− HMAC or Authenticated Encryption with secret key
Must be verified pre-deserialization!
− Don’t read credentials with readObject()
− readUTF() is probably OK
Pro-tip: Don’t leak crypto keys!
− Path traversal
− Default key or key committed to source control
Authenticate
Trust Verify

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Strict firewall rules for deserializing listeners
Sandboxing/Hardening
− Java SecurityManager
− Transient usage can by circumvented by “deferred execution bypass gadgets”
− AppArmor/SELinux
− Docker containers
− Block (or whitelist) forking processes,
file/network I/O
Security-in-depth
Assume breach of defenses

95. 95
Find more unsafe deserialization
− Watch products with naïve mitigations
Find more gadgets/chains
Gadget finding tool improvements
Explore mediums, platforms, formats, implementations
Help with ysoserial
− Has become more active
− Needs contributors
− Lots of work to be done
Great Job Everyone…but you’re not done
Continue pwning all the things

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The Future

97. 97
Stefan Esser, 2009/11/1, Shocking News in PHP Exploitation
− https://www.nds.rub.de/media/hfs/attachments/files/2010/03/hackpra09_fu_esser_php_exploits1.pdf
David Byrne, Rohini Sulatycki, 2010/6/21, Beware of Serialized GUI Objects Bearing Data
− https://www.blackhat.com/presentations/bh-dc-10/Byrne_David/BlackHat-DC-2010-Byrne-SGUI-slides.pdf
Stefan Esser, 2010/7/29, Utilizing Code Reuse/ROP in PHP Application Exploits
− https://www.owasp.org/images/9/9e/Utilizing-Code-Reuse-Or-Return-Oriented-Programming-In-PHP-Application-Exploits.pdf
Wouter Coekaerts, 2011/9/9, Spring Vulnerabilities
− http://wouter.coekaerts.be/2011/spring-vulnerabilities
Charlie Sommerville, 2013/1/10, Rails 3.2.10 Remote Code Execution
− https://github.com/charliesome/charlie.bz/blob/master/posts/rails-3.2.10-remote-code-execution.md
Arseniy Reutov, 2013/5/28, PHP Object Injection Revisited
− https://prezi.com/5hif_vurb56p/php-object-injection-revisited/
Stephen Coty, 2013/6/14, Writing Exploits for Exotic Bug Classes: unserialize()
− https://www.alertlogic.com/blog/writing-exploits-for-exotic-bug-classes/
Ben Murphy, 2013/6/23, Property Oriented Programming Applied to Ruby
− http://slides.com/benmurphy/property-oriented-programming#/
Robert Heaton, 2013/7/22, How to hack a Rails app using its secret_token
− http://robertheaton.com/2013/07/22/how-to-hack-a-rails-app-using-its-secret-token/
Dinis Cruz, 2013/8/6, Using XMLDecoder to execute server-side Java Code on an Restlet application
− http://blog.diniscruz.com/2013/08/using-xmldecoder-to-execute-server-side.html
Past Work / References

98. 98
Abraham Kang, Dinis Cruz, Alvaro Munoz, 2013/8/6, RESTing on your laurels will get you pwned
− http://www.slideshare.net/DinisCruz/res-ting-on-your-laurels-will-get-you-powned4-3
Tom Van Goethem, 2013/9/11, WordPress < 3.6.1 PHP Object Injection
− https://vagosec.org/2013/09/wordpress-php-object-injection/
David Jorm, 2013/11/20, Java Deserialization Flaws: Part 1, Binary Deserialization
− https://securityblog.redhat.com/2013/11/20/java-deserialization-flaws-part-1-binary-deserialization/
Alvaro Munoz, 2013/12/16, CVE-2011-2894: Deserialization Spring RCE
− http://pwntester.com/blog/2013/12/16/cve-2011-2894-deserialization-spring-rce/
Dinis Cruz, 2013/12/22, XStream "Remote Code Execution" exploit on code from "Standard way to serialize and deserialize Objects
with XStream" article,
− http://blog.diniscruz.com/2013/12/xstream-remote-code-execution-exploit.html
David Jorm, 2014/1/23, Java deserialization flaws: Part 2, XML deserialization
− https://securityblog.redhat.com/2014/01/23/java-deserialization-flaws-part-2-xml-deserialization/
Johannes Dahse, Nikolai Krein, Thorsten Holz, 2014/11/3, Code Reuse Attacks in PHP: Automated POP Chain Generation
− https://websec.files.wordpress.com/2010/11/rips_ccs.pdf
− http://syssec.rub.de/media/emma/veroeffentlichungen/2014/09/10/POPChainGeneration-CCS14.pdf
Renaud Dubourguais, Nicolas Collignon, 2013, JSF ViewState upside-down
− http://www.synacktiv.com/ressources/JSF_ViewState_InYourFace.pdf
Gabe Lawrence, Chris Frohoff 2015/1/28, Marshalling Pickles
− http://frohoff.github.io/appseccali-marshalling-pickles/
Past Work / References

99. 99
Matthias Kaiser, 2015/10/28, Exploiting Deserialization Vulnerabilities in Java
− http://www.slideshare.net/codewhitesec/exploiting-deserialization-vulnerabilities-in-java-54707478
− https://www.youtube.com/watch?v=VviY3O-euVQ
Stephen Breen, 2015/11/6, What Do WebLogic, WebSphere, JBoss, Jenkins, OpenNMS, and Your Application Have in Common? This
Vulnerability.
− http://foxglovesecurity.com/2015/11/06/what-do-weblogic-websphere-jboss-jenkins-opennms-and-your-application-have-in-common-this-vulnerability/
Bernd Eckenfels, Gary Gregory, 2015/11/10, Apache Commons statement to widespread Java object de-serialisation vulnerability
− https://blogs.apache.org/foundation/entry/apache_commons_statement_to_widespread
@Zerothoughts, 2016/1/21, Fun with JNDI remote code injection, Spring framework deserialization RCE
− http://zerothoughts.tumblr.com/post/137769010389/fun-with-jndi-remote-code-injection
− http://zerothoughts.tumblr.com/post/137831000514/spring-framework-deserialization-rce
Laksh Raghavan, 2016/1/21, Lessons Learned from the Java Deserialization Bug
https://www.paypal-engineering.com/2016/01/21/lessons-learned-from-the-java-deserialization-bug/
Michael Stepankin, 2016/1/25, PayPal Remote Code Execution Vulnerability
− http://artsploit.blogspot.com/2016/01/paypal-rce.html
Alvaro Muñoz, Christian Schneider, 2016/3/4, Serial Killer: Silently Pwning Your Java Endpoints , Perils of Java Deserialization
− http://rsaconference.com/writable/presentations/file_upload/asd-f03-serial-killer-silently-pwning-your-java-endpoints.pdf
− http://community.hpe.com/t5/Security-Research/The-perils-of-Java-deserialization/ba-p/6838995
2016/3/14 Gabe Lawrence, Deserialization is bad, and you should feel bad
− http://www.meetup.com/OWASP-Cork/events/229340488/
Past Work / References

100. 100
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Qualcomm is a trademark of Qualcomm Incorporated, registered in the United States and other countries.
Other products and brand names may be trademarks or registered trademarks of their respective owners
Thank you
Follow us on:
Gabe Lawrence
gabe@qualcomm.com
@gebl
Chris Frohoff
cfrohoff@qualcomm.com
@frohoff