Memory Attacks and Protection
through Software Diversity
Fall 2014
Presenter: Kun Sun, Ph.D.
Outlines


What is SoK paper?
Two SoK papers
1. Eternal War in Memory

2.

László Szekeres*, Mathias Payer, Tao Wei, Dawn Song, ,
IEEE Symposium on Security and Privacy, 2013.
Automated Software Diversity
Per Larsen, Andrei Homescu*, Stefan Brunthaler, Michael
Franz, IEEE Symposium on Security and Privacy, 2014.
*Thank Laszlo and Andrei for sharing their slides.
What is SoK paper?
Systematization of Knowledge (SoK), in IEEE
s&p conference, since 2010
Papers provide a high value to our community
but may not be accepted because of a lack of
novel research contributions.





survey papers that provide useful perspectives on
major research areas;
papers that support or challenge long-held beliefs
with compelling evidence,
or papers that provide an extensive and realistic
evaluation of competing approaches to solving
specific problems.
3
SoK paper
The goal is to encourage work that evaluates,
systematizes, and contextualizes existing
knowledge.




identify areas that have enjoyed much research
attention,
point out open areas with unsolved challenges,
and present a prioritization that can guide
researchers to make progress on solving important
challenges.
Part I: Eternal War in Memory



C/C++ is unsafe
Everybody runs C/C++ code
They surely have exploitable
vulnerabilities
Overview




What are the attacks?
What are the
deployed protections?
What are the not
deployed protections?
Why aren’t they
deployed?
Attack Model


First step:
 Memory Corruption Attack
Second step:
 Code Corruption Attack
 Control Flow Hijacking
 Data-only Attack
 Information leak
Memory Corruption Attack

Memory errors (bugs)


C and C++ are inherently memory unsafe.


allow the attacker to read and modify the
program’s internal state in unintended ways.
writing an array beyond its bounds,
dereferencing a null-pointer, or reading an
uninitialized variable result in undefined
behavior
Finding and fixing all the programming
bugs is infeasible
Memory Corruption


More aggressive behavior: attacker
changes internal program state
Most often: memory contents



Values of variables on stack/heap
Code pointers
Attack vectors




Buffer overflows
Use-after-free/double-free
Uninitialized variables
Format strings
Classic Stack Smashing Attack
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Use-after-free Exploits
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Heap overflow
Corrupting Newer Pointers
Modify a
data pointer
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Attack Model


First step:
 Memory Corruption Attack
Second step:
 Code Corruption Attack
 Control Flow Hijacking
 Data-only Attack
 Information leak
Modifying the code itself
Modify a
data pointer
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify
code ...
Modify a
code pointer...
… to attacker
specified code
… to target
code address
Code
corruption
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Code Integrity
Modify a
data pointer
ReadModify
only
code ...
… code
to attacker
specified
pagescode
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Challenge: In just-in-time compilation, a small time window
when the generated code is on a writable page.
Attack Model


First step:
 Memory Corruption Attack
Second step:
 Code Corruption Attack
 Control Flow Hijacking
 Data-only Attack
 Information leak
Control Flow Hijacking

Attacker takes control of program
execution
 Program executes code under attacker
control
 Other name: arbitrary code execution
Non-executable data
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
e.g., Stack
Non-executable data
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
Inserted Shellcode can
not be executed.
Return-oriented programming
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
Return integrity
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
Return integrity
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
UseStack
pointer by
ret
instruction
canaries
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
Hijacking Indirect Calls and Jumps
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
UseStack
pointer by
ret
instruction
canaries
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
23
Address Space Randomization
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
code address
Use pointer by
indir. call/jmp
UseStack
pointer by
ret
instruction
canaries
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
Address Space Randomization
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
… to target
ASLR
code
address
Use pointer by
indir. call/jmp
UseStack
pointer by
ret
instruction
canaries
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
Attack Model


First step:
 Memory Corruption Attack
Second step:
 Code Corruption Attack
 Control Flow Hijacking
 Data-only Attack
 Information leak
Data-only Attack

The target of the corruption can be any
security critical data in memory,
 Security critical variables
 configuration data
 the representation of the user identity
 or keys.
Program Data Tampering


Interfere with program execution
Examples
 Bypassing DRM/copy protection
 Videogame cheating
 FPE, GW (DoS)
 Online game?
Data-only attack
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
Modify
data ...
… to target
ASLR
code
address
… to attacker
specified value
Use pointer by
indir. call/jmp
UseStack
pointer by
ret
instruction
canaries
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Attack Model


First step:
 Memory Corruption Attack
Second step:
 Code Corruption Attack
 Control Flow Hijacking
 Data-only Attack
 Information leak
Information Leaks

Steal program information/state in memory,
process metadata, registers, and files, etc.
1.
2.

Valuable information by itself, e.g. credit card,
password, encryption key.
Facilitating further attacks, e.g., memory addresses
to bypass ASLR
Side channel attacks
Information leakage
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
Modify
data ...
Output
data
… to target
ASLR
code
address
… to attacker
specified value
Interpret the
leaked value
Use pointer by
indir. call/jmp
UseStack
pointer by
ret
instruction
canaries
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Information
leak
Bypassing ASLR with user scripting
Modify a
data pointer
Readonly
Modify
code ...
code
… pages
to attacker
specified code
Code
corruption
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify a
code pointer...
Modify
data ...
Output
data
… to target
code address
… to attacker
specified value
Interpret the
leaked value
Use pointer by
indir. call/jmp
UseStack
pointer by
ret
instruction
canaries
Exec. gadgets
or functions
NonExecute
exec.
injected
code
data
pages
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Information
leak
Overview




What are the attacks?
What are the
deployed protections?
What are the not
deployed protections?
Why aren’t they
deployed?
Protection Techniques

Deterministic Protection


A low level reference monitor (RM) enforce a
deterministic safety policy.
 By hardware, like W⊕X
 By software, adding RM into code
Probabilistic Protection

Built on randomization or encryption
 Instruction Set Randomization
 Address Space Randomization
 Data Space Randomization
Hijack
protection
Deployed Protections
Policy
Technique
Weakness Perf
.
Comp.
W⊕X
Page flags
JIT
1x
Good
Return integrity
Stack
cookies
Direct
overwrite
1x
Good
Address space
rand.
ASLR
Info-leak. 1.1x
Good
Overview




What are the attacks?
What are the
deployed protections?
What are the not
deployed protections?
Why aren’t they
deployed?
Control-flow Integrity
Modify a
data pointer
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify
code ...
Modify a
code pointer...
Modify
data ...
Output
data
… to attacker
specified code
… to target
code address
… to attacker
specified value
Interpret the
leaked value
Code
corruption
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Information
leak
Control-flow integrity
Modify a
data pointer
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify
code ...
Modify a
code pointer...
Modify
data ...
Output
data
… to attacker
specified code
… to target
code address
… to attacker
specified value
Interpret the
leaked value
Use pointer by Use pointer by
CFIret instruction
indir. call/jmp
Use corrupted
data variable
Exec. gadgets
or functions
Code
corruption
Execute
injected code
Control-flow
hijack
Data-only
attack
Information
leak
CFI
p = &f
jmp p
f() {
…
}
q = &g
jmp q
g() {
…
}
CFI
ID
p = &f
jmp p
f() {
…
}
ID
q = &g
jmp q
g() {
…
}
CFI
ID
check ID
p = &f
jmp p
f() {
…
}
ID
check ID
q = &g
jmp q
g() {
…
}
CFI
ID
check ?
p = &f
jmp p
if (…)
q = &f
else
q = &g
check ? jmp q
f() {
…
}
ID
g() {
…
}
Over-approximation problem
ID
check ID
p = &f
jmp p
if (…)
q = &f
else
q = &g
check ID jmp q
f() {
…
}
ID
g() {
…
}
Over-approximation problem
ID
check ID
p = &f
jmp p
if (…)
q = &f
else
q = &g
check ID jmp q
printf() {
…
}
ID
system() {
…
}
Modularity problem
ID
printf() {
…
}
ID
system() {
…
}
CFI
Hijack protection
Policy
Technique
W⊕R
Return integrity
Address space
rand.
Control-flow integ.
Weakness
Page flags
JIT
Stack Direct
cookies overwrite
ASLR
Perf
.
Comp.
1x Good
1x
Good
Info-leak. 1.1x
Good
CFI Over-approx.
1.4x
Librarie
s
Memory Safety
Modify a
data pointer
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify
code ...
Modify a
code pointer...
Modify
data ...
Output
data
… to attacker
specified code
… to target
code address
… to attacker
specified value
Interpret the
leaked value
Code
corruption
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Information
leak
Memory safety
Make pointer
Make pointer
Pointer
out-of-bounds
dangling
metadata
tracking &
Use pointer
Use pointer
checking
to write
to read
Modify a
data pointer
Modify
code ...
Modify a
code pointer...
Modify
data ...
Output
data
… to attacker
specified code
… to target
code address
… to attacker
specified value
Interpret the
leaked value
Code
corruption
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Information
leak
Data integrity
Modify a
data pointer
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify
code ...
Modify a
code pointer...
Modify
data ...
Output
data
… to attacker
specified code
… to target
code address
… to attacker
specified value
Interpret the
leaked value
Code
corruption
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Information
leak
Data integrity
Modify a
data pointer
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify
Modify a
Modify
Output
data
… to attacker
specified code
… to target
code address
… to attacker
specified value
Interpret the
leaked value
Object
& checking data ...
code ...metadata tracking
code pointer...
Code
corruption
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Information
leak
Data-flow integrity
Modify a
data pointer
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify
code ...
Modify a
code pointer...
Modify
data ...
Output
data
… to attacker
specified code
… to target
code address
… to attacker
specified value
Interpret the
leaked value
Code
corruption
Use pointer by
indir. call/jmp
Use pointer by
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Information
leak
Data-flow integrity
Modify a
data pointer
Make pointer
out-of-bounds
Make pointer
dangling
Use pointer
to write
Use pointer
to read
Modify
code ...
Modify a
code pointer...
Modify
data ...
Output
data
… to attacker
specified code
… to target
code address
… to attacker
specified value
Interpret the
leaked value
Code
corruption
Use pointer by
indir. call/jmp
Use pointer by
DFI
ret instruction
Exec. gadgets
or functions
Execute
injected code
Control-flow
hijack
Use corrupted
data variable
Data-only
attack
Information
leak
Generic
protection
Hijack protection
Summary
Policy
Technique
Weakness Perf
.
Comp.
W⊕R
Page flags
JIT
1x
Good
Return integrity
Stack
cookies
Direct
overwrite
1x
Good
Address space
rand.
ASLR
Info-leak. 1.1x
Good
Control-flow integ.
CFI
Over-approx. 1.4x
Librarie
s
Memory safety
SB+CETS
None 2-4x
Good
Data integrity
WIT
Over- 1.2x
approx.,…
Librarie
s
Data space rand.
DSR
Over- 1.3x
approx.,…
Librarie
s
Data-flow integrity
DFI
Over-approx. 2-3x
Librarie
s
Challenges in Practical Usage

Why most of defense mechanisms are not used
in practice?
1.
the performance overhead of the approach
outweighs the potential protection,
2.
the approach is not compatible with all
currently used features (e.g., in legacy
programs),
3.
the approach is not robust and the offered
protection is not complete,
4.
or the approach depends on changes in the
compiler toolchain or in the source-code
while the toolchain is not publicly available.
55
Run-time Performance

Performance significantly impacts adoption

Lowest overhead (negligible)




DEP
ASLR
Stack canaries
Diversity/performance trade-off


Pre-distribution: small overhead (1-11%)
Post-distribution: larger overhead (5-265%)
Part II: Automated Software Diversity

Security Problem
 Attacks rely on offline information of
target



Memory layout
Memory contents (including program code)
Deterministic algorithms
In one word: predictability
Huge advantage for attacker



Attack one instance of program => attack
them all
Probabilistic Protection

Deterministic Protection


A low level reference monitor (RM) enforce a
deterministic safety policy.
 By hardware, like W⊕X
 By software, adding RM into code
Probabilistic Protection

Built on randomization or encryption
 Instruction Set Randomization
 Address Space Randomization
 Data Space Randomization
Deterministic vs. Nondeterministic algorithm


Deterministic algorithm, given a particular input,
will always produce the same output, always
passing through the same sequence of states.
Nondeterministic algorithm, even for the same
input, exhibit different behaviors on different runs.



uses external state, e.g., user input, a global variable, a
hardware timer value, a random value, or stored disk
data.
timing-sensitive operations, e.g., multiple processors
writing to the same data at the same time.
hardware errors causing state change in an unexpected
way.
Software Diversity
Threat (Why Diversity?)



Information Leaks
Memory Corruption Attacks
Control Flow Hijacking





Code Injection
Code Reuse
Program Tampering
Reverse Engineering
Combination of the above
Reverse Engineering




Goal: discover program semantics (algorithms)
Attacker has access to program binary
security-through-obscurity
Most frequent mitigation: obfuscation
What Have We Learned?

Attacks are increasing in complexity

Work around defenses (incl. diversity)

Multi-tiered attacks
Example: JIT Code Reuse

State-of-the-art multi-tier attack





Attacker finds address of valid code
Uses information leak to read all code pages
Scan code pages for reusable code snippets
(ROP gadgets)
Redirect control flow to attack payload
(memory corruption)
Ultimate goal: control flow hijacking and more
K. Z. Snow, F. Monrose, L. V. Davi, A. Dmitrienko, C. Liebchen, and A.-R. Sadeghi.
Just-in-time code reuse: On the effectiveness of fine- grained address space layout
randomization. In Proceedings of the 34th IEEE Symposium on Security and Privacy, S&P
’13, 2013.
Example: Blind ROP

Novel ROP attack (from S&P 2014)
 Blind information leak
 Locate gadgets by trial-and-error
 Build gadget chain that writes memory
to socket
 Used to leak entire program binary
 Requires no a priori knowledge of
program
What to Diversify?

Program Code




Control Flow Hijacking
Reverse Engineering
Program Tampering

Program Data



Information Leaks
Memory Corruption
Program Tampering
Granularity of Transformations
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Instruction-level
Basic block-level
Loop-level
Function-level
Program-level
System-level
Diversifying Transformations
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Instruction-level
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Basic block-level
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Instruction Substitution
Equivalent Instructions
Instruction Reordering
Register Allocation
Randomization
Garbage Code Insertion
Basic Block Reordering
Opaque Predicates
Branch Function Insertion
Loop-level
Diversifying Transformations
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Function-level
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Program-level
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Stack Layout Rand.
Function Parameter Rand.
Randomized Inlining/Outlining/Splitting
Control Flow Flattening
Function Reordering
Base Address Rand. (ASLR)
Program Encoding Rand.
Data Randomization
Library Entry Point Rand.
System-level
When to Diversify?
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Design
Implementation
Compilation
Linking
Installation
Loading
Execution
Update
Pre-distribution Diversification
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Disassembly is hard!
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Indirect branches (not known until running
time)
Data inside code section
Compile-time information makes
diversification easier
 Garbage Code Insertion
 Register Allocation Randomization
 Stack Layout Randomization
 more...
Post-distribution Diversification
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Distributed diversification
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Lower costs for developers
Introduces latency
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Generally faster diversification
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More diversity
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Between each run
During execution
Security
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Entropy
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Logical/formal argument
Concrete attacks
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Measure entropy/# of different versions
Quantitative, not qualitative
ASLR: entropy matters!!!
Test a real attack against hardened binary
Attack-specific metrics
Moving Forward
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Hybrid Approaches
Error Reporting & Debugging
Automated Security Evaluation
Side-channels / Information Leaks
Reference
1.
Per Larsen, Andrei Homescu, Stefan Brunthaler, and Michael Franz. 2014. SoK:
Automated Software Diversity. In Proceedings of the 2014 IEEE Symposium on
Security and Privacy (SP '14).
2.
Laszlo Szekeres, Mathias Payer, Tao Wei, and Dawn Song. 2013. SoK: Eternal War in
Memory. In Proceedings of the 2013 IEEE Symposium on Security and Privacy (SP
'13).
3.
Pucella, R.; Schneider, F.B., "Independence from obfuscation: a semantic framework
for diversity," Computer Security Foundations Workshop, 2006. 19th IEEE , vol., no.,
pp.12 pp.,241
4.
K. Z. Snow, F. Monrose, L. V. Davi, A. Dmitrienko, C. Liebchen, and A.-R. Sadeghi.
Just-in-time code reuse: On the effectiveness of fine- grained address space layout
randomization. In Proceedings of the 34th IEEE Symposium on Security and Privacy,
S&P ’13, 2013.
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Questions?