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,A Survey onRuntime Smashed Stack Detection,Background,Vulnerability becomes Serious Social Problems,ex),Morris Worm on UNIX in 1988,Code Red on Windows in 2001,Nimda on Windows in 2001,Root DNS Attack in 2002,CERT/CC Advisories,Dominant Attacks,are caused by,Buffer Overflow,Buffer Overflow Attack,Stack Smashing Attack,Common mode of buffer overflow attack for hijacking system control,Hijack Process,Inject the attack code,All applications are ready for injection,Force the process to execute the injected code,Stack buffer overflow vulnerability allow malicious input to overwrite the return address and to snatch the execution flow,Text Area,(program),Data Area,Stack Area,Malicious Code,Stack Smashing Attack (1),Program Structure of C like languages,int main (int argc, char *argv),calc_something(x, y);,show_something();,return 0;,void calc (int n),void calc_something (int x, int y),calc(x);,Stack Smashing Attack (2),Flow Control Data,int main (int argc, char *argv),calc_something(x, y);,return 0;,void calc (int n),void calc_something (int x, int y),calc(x);,First In Last Out Buffer,main: line n,calc_something: line m,Stack Smashing Attack (3),Local Variables,Allocated in FILO buffer,unified with flow control data,void calc (int n),int a, b;,char buffer1024;,foo();,bar();,return address,char buffer1024;,int b;,int a;,Local Variables,of,calc(),Stack Frame,of,calc(),Stack Smashing Attack (4),Injections and Hijacks,return address,char buffer1024;,int b;,int a;,malicious code,overwritten by buffer overflow,as buffer1024, , buffer1027,0x046424,Malicious Code,0x046424,Approaches (1),Software Approaches,Novel secure program languages or perfect programs without bugs,Compiler approaches without fixing each source program,Static Analysis,A First Step Towards Automated Detection of Buffer Overrun Vulnerabilities,“pointer can not be analyzed perfectly,Runtime Detection,LibSafe (LibVerify) wrapper library,StackGuard,StackShield,ProPolice,Approaches (2),Hardware Approaches,Non-Exec Pages,NonExecutable User Stack,vs return-into-libc attack,signal handling,NonExecutable Data Pages,modified dynamic loader,modified just-in-time (JIT) compiler,Secure Return Address Stack (SRAS),Architecture Support for Defending Against Buffer Overflow Attacks,A Processor Architecture Defense against Buffer Overflow Attacks,Secure Cache,A Cache Architecture to Prevent Malicious Code Executions,Secure Return Address Stack (1),Concept,Return-Address-Stack (RAS),implemented at fetch or issue stage on modern processors,Pentium, Alpha, SPARC, POWER,monitor the instructions which mean “call and “return,call: push current program counter to the RAS,return: pop an address from the RAS,for improvement of execution path prediction,but RAS is not perfectly matched with the real call stack,speculative update with branch prediction,RAS table overflow,Detect mismatches between RAS and Stack information,raise exception,Secure Return Address Stack (2),Improvement,Implement another RAS at commit stage,avoid speculative update,Table optimization,overflow handling,swap to/from main memory with hardware or OS support,enough size for the majority,64 entry,in the case of SPEC2000,Secure Return Address Stack (3),Non-FILO Control Flow Operation Problems,setjmp/longjmp Functions,C+ Exceptions,Multi Threading,Tail Recursion,(handmade eccentric assembly language programs!),these are often historical and critical :-),Problem & Solution,these codes access and modify the call stack directly,cause mismatches between RAS and Stack information,we can not treat these codes transparently with SRAS approach,special instruction,sras_push,and,sras_pop,are required for stack operation,Secure Cache (1),Concept,Duplicate Cache-lines as read-only Replica-lines,Detect return address mismatches,between Cache-lines and Replica-lines,return address,Cache Line,Replica Line,return address,malicious data,mismatch,Secure Cache (2),Advantages,Efficient spaces without swap,Transparent support for Non-FILO Control Flow Operations,Disadvantage,Detection is not perfect,Lose replica information on cache line replacement,Commercial Implements,NXBit / Execute Disable Bit,AMD - Opteron / Athlon64,Intel - Itanium / Pentium4,Transmeta - Efficeon,SmartMIPS ASE,Secure Memory Spaces,Interpreted Language Acceleration,Cryptography Acceleration,SecureCore (ARM),Memory Protection Unit,Jazelle Technology,Cryptography Acceleration,TrustZone (ARM),programs marked as trusted run with high level privilege and can access data in secure zone,Conclusion,Stack Smashing Attacks is important security problem,Hardware approaches achieve more transparent way,without modifications of applications,Realization of true transparent detection is difficult,Non-FILO Control Flow Operation Problems,setjmp/longjmp Functions,C+ Exceptions,Multi Threading,Tail Recursion,But cool idea might realize sufficiently transparent detection,
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