defeating public exploit protections (emet v5.2 and more)
TRANSCRIPT
Defeating public exploit protections (EMET v5.2 and more)
Raghav PandeResearcher @ FireEye
Disclaimer
The Content, Demonstration, Source Code and Programs presented here is "AS IS" without any warranty or conditions of any kind. Also the views/ideas/knowledge expressed here are solely mine and have nothing to do with the company or the organization in which i am currently working.
However in no circumstances neither me nor SecurityXploded is responsible for any damage or loss caused due to use or misuse of the information presented here.
Content
Introduction to Exploitation
Public Protections
Bypass
Precisely Targeted
Why Exploits?
Difficult to understand
No proper intel
Can own a Researcher and Newbie alike
You really need to know your stuff
Information
Tools used are public and free
EMET (Microsoft)
Anti Exploit (Malware Bytes)
Hitman Alert (Surfright)
Note: They do a very good job in protecting end users, But nothing is perfect.
Kudos to them!
Introduction to Exploitation
Exploits are crafted pieces of Art which can elevate a Software Bug and grant you one time access to Code Execution.
Loopholes or Logic Bugs
Memory Corruption
Information Disclosure
Introduction to Exploitation
Details
Pre Exploitation or SetupSpray
Corruption of Meta-Information
InfoLeak
ExploitationCorruption
Payload ExecutionROP
CodeExecution
Post ExploitationMalware
Possible Protections
Pre Exploitation or SetupSpray
ExploitationPayload Execution
ROP detection
CodeExecution detection
Post ExploitationMalware
Public Protections3rd Party support
MemProt
RopCallerCheck
StackPivot
SimExecFlow
LoadLibrary
Shellcode Protection
OS & Processor supported
ASLR (Enforced)
DEP (Enforced)
Exploitation
CVE-2012-1876
IE exploitCorruption of HeapData by Overflow
ROP
Shellcode to pop calc.exe
Hurdles
Rop Detection
Shellcode Detection
ASLR
DEP
Exploitation
Defeat DEP by ROP
Defeat ASLR by memory leak (provided in sample exploit)
Crux of Exploitation Detection techniques
Exploitation Detection Hurdles leftROP
Shellcode
Defeating protections from Stack based exploits is for next meetup probably.
Exploitation
In the End
Most of browser based vulnerabilities can be used to cover ASLR by leaking memory to form a valid ROP Chain.
Nearly all exploits come down to
1. Spray2. ROP3. Shellcode
So we will focus on bypassing these only.
Protections StackPivot Check (ROP)
ProtectionsCallerCheck & SimExecFlow Check
(ROP)
Protections Payload Check (Shellcode)
Protections EAF Check (EMET)
DifferentiateEMET MBAE HITMAN Alert
Rop StackPivot Yes Yes Yes
Rop CallerCheck Yes (Full) Yes (Dummed) Yes (Dummed)
Rop SimExecFlow
Yes No No
Payload (Shellcode)
No Yes Yes
ControlFlow Integrity(Rop)
No No Yes
EAF Yes No No
Image Highjack No Yes Yes
Bypassing
StackPivot
CallerCheck
SimExecFlow
EAF/Payload Check
CFI
Bypassing Stackpivot
Bypassing Stackpivot
Bypassing CallerCheck & SimExecFlow
Bypassing CFI
Null out LBR before ApiCall
Borrow functions (hard, unless automated)
Be Creative (what we did)
Note: We bypassed a public implementation of CFI, doesn’t mean if its implemented another way it can still be bypassed the same way.
Bypassing CFI
Bypassing Payload Check
Bypassing All protections
In All public exploit mitigation toolkits (Generic)
DEMO time
Bypassing All protections
StackPivot
Targeted Bypassing
EMET
0x779fe695 + poi(0x779fe695 + 1) => 0x37df11d0
Targeted Bypassing
EMET
0x37df11d0+0x26 => Preserved Function Prologue
Jumping into Preserved Function Prologue bypasses Hook and forms a valid api call chain
Targeted Bypassing
“Other Tools”
Just like EMET we can bypass other public and free toolkits as well.
However, That is not the scope of this presentation. =)
Conclusion
An attacker who has studied the system can break anything & everything.
Best method of protecting yourself is using a custom protection, and never letting the adversary know what you use.
Queries?