DOCSLIB.ORG

S3library: Automatically Eliminating C/C++ Buffer Overflow Using

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
S3library: Automatically Eliminating C/C++ Buffer Overflow Using S3Library: Automatically Eliminating C/C++ Buffer Overflow using Compatible Safer Libraries Kang Sun, Daliang Xu, Dongwei Chen, Xu Cheng, Dong Tong Department of Computer Science and Technology, Peking University {ajksunkang, xudaliang, chendongwei, tongdong}@pku.edu.cn, [email protected] Abstract buffer overflows. These contiguous overflows still cover over 40 percent in real-world exploitation [3]. Early designers of Annex K of C11, bounds-checking interfaces, recently in- standard C (specifically ANSI) over-trusted the programmers. troduced a set of alternative functions to mitigate buffer over- A host of vulnerable functions calls they provide, such as flows, primarily those caused by string/memory functions. gets, strcpy and memcpy, neither make bounds checking to However, poor compatibility limits their adoption. Failure determine whether the destination buffer is big enough nor oblivious computing can eliminate the possibility that an at- have the size information needed to perform such checks. tacker can exploit memory errors to corrupt the address space and significantly increase the availability of systems. Annex K of C11, Bounds-checking interfaces [19, 37, 45], In this paper, we present S3Library (Saturation-Memory- recently proposed a set of new, optional alternative library Access Safer String Library), which is compatible with functions that promote safer, more secure programming. The the standard C library in terms of function signature. Our apparent difference (we will explain in later section) is that s size technique automatically replaces unsafe deprecated memo- the APIs have _ suffix and take an additional argu- ry/string functions with safer versions that perform bounds ment explicitly passed by programmers. Intuitively, adopting checking and eliminate buffer overflows via boundless mem- these APIs in an existing code requires non-trivial modifi- ory. S3Library employs MinFat, a very compact pointer rep- cations leading to poor compatibility and guidance. This is resentation following the Less is More principle, to encode the main reason why the new APIs continue to be controver- metadata into unused upper bits within pointers. In addition, sial [12,26,38], despite almost a decade since its introduction. S3Library utilizes Saturation Memory Access to eliminate Furthermore, there is almost no viable conforming implemen- illegal memory accesses into boundless padding area. Even if tation [24] applying the bounds-checking interfaces without an out-of-bounds access is made, the faulty program will not considerable origin code changes. be interrupted. We implement our scheme within the LLVM Various modern techniques have been proposed to enforce framework on X86-64 and evaluate our approach on correct- memory safety, both statically and dynamically. Static analy- ness, security, runtime performance and availability. sis [25,41 –43] that automatically transforming C programs at source code level is hard to obtain a complete coverage be- cause a certain type of size information is only available at run- arXiv:2004.09062v1 [cs.CR] 20 Apr 2020 1 Introduction time. Dynamic defense mechanisms [7, 13, 21, 22, 28, 30, 39] augment the original unmodified program with metadata Buffer overflows remain a major threat to the security of de- (bounds of live objects or allowed memory regions) and insert pendable computer systems today [44]. Applications written bounds checking against this metadata before every memory in low-level languages like assembly or C/C++ are prone to access for runtime detection. They all leave libraries uninstru- buffer overflow bugs. From 2008 to 2014, nearly 23 percent of mented and introduce manually written wrapper to maintain all severe software vulnerabilities were buffer errors, and 72 the compatibility, performing simple bounds checking before percent of buffer errors were serious [16]. In 2018, among the calling a real legacy function. However, all existing software- 16,556 security vulnerabilities recorded by the NIST National based bounds-checking solutions exhibit high performance Vulnerability Database [4], 2,368 (14.3%) were overflow vul- overhead (50-150%), preventing them from wide adoption in nerabilities. Meanwhile, buffer overflow is listed as the first production runs. Address Sanitizer [39] is currently better in position in Weaknesses CWE Top 25(2019) [1]. terms of usability, but it is built for debugging purposes and The danger inherent in the use of unsafe standard C library suffers from detecting non-contiguous out-of-bounds viola- calls, especially the string/memory functions, presents classic tions. Intel MPX [30] provides a promising hardware-assisted 1 full-stack technique, but its implementation is proved not as (a) Look-up Table (b) Fat Pointer (c) Tagged Pointer good enough as expected. Most of these approaches provide complete protection for buffer overflow violations, detecting second trie both contiguous and non-contiguous overflows, but have rela- LB UB key lock tively high runtime overhead. primary trie Performing bounds checking is costly due to large amounts of metadata management: the metadata describing the object bounds must be recorded, propagated and retrieved to check Object Object Object numerous times. Among these processes, the checking is the × × bottleneck. For each pointer dereference, metadata must be √ √ loaded from memory/in-pointer to verify the validation of the pointer. Once the pointer is out of bounds, it also gives Pointer Pointer Pointer A much pressure on the branch predictor and pipeline to handle Base exceptions. As a result, the checking process accounts for the Bound vast majority of execution time. In this paper, we propose an interesting idea in the explo- ration space to concentrate only on buffer overflows caused by Figure 1: Pointer-based approach. highly-critical memory/string functions, rather than bounds checking on each memory reference. With this “partial” mem- ory safety, we wonder what trade-off we can achieve between 2 Background security and overhead. Meanwhile, we propose a feasible im- plementation of Safe C Library without any modification to 2.1 Memory Safety existing C programs. We present MinFat and S3Library, an interesting approach Enforcing Memory Sa f ety stops all memory corruption ex- to automatically replace unsafe deprecated functions like ploits. Existing runtime techniques that guarantee spatial and strcpy with safer versions that perform bounds checking and temporal memory safety can be broadly categorized into two eliminate buffer overflows via boundless memory. MinFat classes: object-based approach and pointer-based approach. is based on the tagged pointer [20, 40] scheme that trans- Object-based approaches [18, 35, 39] associate metadata with parently encodes bounds meta information of buffer (stack, the location of the object in memory, not with each pointer. heap and global variables) within the pointer itself. We fol- The significant drawback is that its implementations are gener- low the principle of Less is More and adopts a very compact ally incomplete because they are unable to provide an accurate encoding scheme inspired by BaggyBounds [7] with the min- bound information for each object. However, an accurate size imum bit-width that allows an effective way to retrieve object information is necessary for the implementation of Safe C bounds. S3Library retains the APIs compatibility with legacy Library to perform bounds checks. Besides, object-based ap- functions, and performs the same bounds checking as Safe proaches are not suitable for non-contiguous buffer overflow C Library. The property of MinFat trades memory for per- detection also due to the lack of accurate bounds information. formance and adds boundless padding [11, 32–34] to every In this section, we focus on eliminating spatial memory object. These boundless memory blocks support Saturation errors (i.e., buffer overflows) using the pointer-based ap- Memory Access (SMA) to isolate the memory errors within proach, which is considered as the only way to support com- S3Library in case the runtime-constraint violation occurs. prehensive memory safety [27]. Pointer-based approaches Overall, this paper makes the following contributions: [7, 13, 21, 22, 28, 30, 47] attach metadata with every pointer, • To the best of our knowledge, S3Library is the first run- bounding the region of memory that pointer can legitimately time solution that applies implementations of Safe C dereference. As presented in Figure1, pointer-based ap- Library without any modification of origin codes. proaches can be categorized into the following three classes according to how current designs store and use metadata. • A thorough analysis and evaluation of the overhead using Look-up Table scheme: SoftBound [28, 29]. This class, MinFat Pointer on selective functions. such as SoftBound, records base and bound metadata in a • We present a buffer overflow elimination mechanism disjoint metadata facility that is accessed by explicit table within Safe C Library and evaluate its performance in look-ups. Figure1(a) shows the way how SoftBound+CETS Section 5.3. organizes pointer metadata in a two-level trie for quick search- ing purpose. With table look-ups, the accurate bound infor- • An LLVM-based prototype of our design implemented in mation can be obtained in time whenever the pointer needs. X86-64 architecture environment, evaluated with respect Unfortunately, this look-up table scheme cannot be considered to security, availability and runtime performance. safe in multithread environments.
Load more

Recommended publications
  • Protecting the Stack with Metadata Policies and Tagged Hardware
    2018 IEEE Symposium on Security and Privacy Protecting the Stack with Metadata Policies and Tagged Hardware Nick Roessler Andre´ DeHon University of Pennsylvania University of Pennsylvania [email protected] [email protected] Abstract—The program call stack is a major source of ex- stack data, or hijack the exposed function call mechanism in ploitable security vulnerabilities in low-level, unsafe languages a host of other malicious ways. like C. In conventional runtime implementations, the underlying Consequently, protecting the stack abstraction is critical stack data is exposed and unprotected, allowing programming errors to turn into security violations. In this work, we design for application security. Currently deployed defenses such as W X and stack canaries [2] make attacks more difficult to novel metadata-tag based, stack-protection security policies for ⊕ a general-purpose tagged architecture. Our policies specifically conduct, but do not protect against more sophisticated attack exploit the natural locality of dynamic program call graphs to techniques. Full memory safety can be retrofitted onto existing achieve cacheability of the metadata rules that they require. C/C++ code through added software checks, but at a high cost Our simple Return Address Protection policy has a performance overhead of 1.2% but just protects return addresses. The two of 100% or more in runtime overhead [3]. These expensive richer policies we present, Static Authorities and Depth Isola- solutions are unused in practice due to their unacceptably high tion, provide object-level protection for all stack objects. When overheads [4]. enforcing memory safety, our Static Authorities policy has a There is a long history of accelerating security policies with performance overhead of 5.7% and our Depth Isolation policy hardware to bring their overheads to more bearable levels has a performance overhead of 4.5%.
    [Show full text]
  • In-Fat Pointer: Hardware-Assisted Tagged-Pointer Spatial Memory Safety Defense with Subobject Granularity Protection
    In-Fat Pointer: Hardware-Assisted Tagged-Pointer Spatial Memory Safety Defense with Subobject Granularity Protection Shengjie Xu Wei Huang David Lie [email protected] [email protected] [email protected] University of Toronto University of Toronto University of Toronto Canada Canada Canada ABSTRACT 1 INTRODUCTION Programming languages like C and C++ are not memory-safe be- Memory corruption vulnerabilities in programs written in non- cause they provide programmers with low-level pointer manipu- memory-safe programming languages like C and C++ have been lation primitives. The incorrect use of these primitives can result a research focus for more than a decade [40]. When a pointer is in bugs and security vulnerabilities: for example, spatial memory dereferenced, errors, causing memory-safety violations, can result safety errors can be caused by dereferencing pointers outside the in the unintended disclosure or corruption of memory. Such errors legitimate address range belonging to the corresponding object. are a powerful primitive for attackers to mount further attacks, While a range of schemes to provide protection against these vul- such as code reuse attacks [34] and data-only attacks [18]. Memory- nerabilities have been proposed, they all suffer from the lack of one safety violations usually result from spatial memory errors, where or more of low performance overhead, compatibility with legacy incorrect pointer arithmetic causes an address to point outside the code, or comprehensive protection for all objects and subobjects. intended memory range when it is dereferenced. We present In-Fat Pointer, the first hardware-assisted defense To detect all spatial memory errors, the value of the pointer that can achieve spatial memory safety at subobject granularity must be checked against pointer bounds, which are metadata that while maintaining compatibility with legacy code and low over- describes the memory range over which the pointer may safely head.
    [Show full text]
  • Fast and Generic Metadata Management with Mid-Fat Pointers
    Fast and Generic Metadata Management with Mid-Fat Pointers ∗ ∗ Taddeus Kroes Koen Koning [email protected] [email protected] Cristiano Giuffrida Herbert Bos Erik van der Kouwe [email protected] [email protected] [email protected] Vrije Universiteit Amsterdam ABSTRACT there is an increasing need for generic and composable de- Object metadata management schemes are a fundamental fense frameworks, which can combine multiple defenses but building block in many modern defenses and significantly disable others to tune the performance-security trade-off affect the overall run-time overhead of a software harden- according to the deployment requirements [23]. Second, we ing solution. To support fast metadata lookup, many meta- need fast pointer-to-object metadata lookup schemes to em- data management schemes embed metadata tags directly in- power such frameworks [12]. A promising strategy to design side pointers. However, existing schemes using such tagged such schemes efficiently is to embed tags inside pointers. pointers either provide poor compatibility or restrict the Two tagged pointer schemes dominate the literature. Fat generality of the solution. pointers change the size and representation of pointers to In this paper, we propose mid-fat pointers to implement support arbitrary metadata tags [4, 14, 19]. This solution fast and generic metadata management while retaining most can support generic defenses with no restrictions, but it is of the compatibility benefits of existing schemes. The key plagued by compatibility problems since pointers radically idea is to use spare bits in a regular 64-bit pointer to encode change their format [6,7]. Low-fat pointers carefully place arbitrary metadata and piggyback on software fault isola- objects in the memory address space to implement the other tion (SFI) already employed by many modern defenses to extreme: no changes in pointer size and representation, and efficiently decode regular pointers at memory access time.
    [Show full text]
  • Maxsim: a Simulation Platform for Managed Applications
    R MaxSim: A Simulation Platform for Managed Applications Open-source: https://github.com/beehive-lab/MaxSim Andrey Rodchenko, Christos Kotselidis, Andy Nisbet, Antoniu Pop, Mikel Lujan Advanced Processor Technologies Group, School Of Computer Science, The University of Manchester Overview R ● What simulation platform for managed applications is needed and why? ● VM Selection Justification: Maxine VM ● Simulator Selection Justification: ZSim ● MaxSim: Overview and Features ● Use Cases: Characterization, Profiling, and HW/SW Co-design ● Conclusion 1 What simulation platform for managed R applications is needed and why? TIOBE Programming Community Index (March 2017) 1. Java 2. C 3. C++ 4. C# 5. Python 6. Visual Basic .NET 7. PHP 8. JavaScript 9. Delphi/Object Pascal 10. Swift Source: www.tiobe.com 25 20 ) % ( s 15 g n i t a 10 R 5 0 2002 2004 2006 2008 2010 2012 2014 2016 2 What simulation platform for managed R applications is needed and why? Specific Characteristics of Managed Applications // Example of a class. Memory class Foo { Stack Heap public long bar; 0x00 } obj:0xd0 // Source code example. 0x40 0xd0 CIP:0x80 { // Allocation site. ... Code Cache 0xd8 <reserved> Object obj = new Foo(); 0x78 0xe0 bar:0x00 ... // GC can happen. ... // Type introspection. 0x80 if (obj instanceof Foo) { Class - reference ... ... } Information - primitive } 0xb8 ● ● Distributed in the verifiable JIT compilation and bytecode format interpretation ● ● Automatic memory Object orientation and management associated metadata 3 What simulation platform for managed
    [Show full text]
  • Inline and Sideline Approaches for Low-Cost Memory Safety in C
    UCAM-CL-TR-954 Technical Report ISSN 1476-2986 Number 954 Computer Laboratory Inline and sideline approaches for low-cost memory safety in C Myoung Jin Nam February 2021 15 JJ Thomson Avenue Cambridge CB3 0FD United Kingdom phone +44 1223 763500 https://www.cl.cam.ac.uk/ c 2021 Myoung Jin Nam This technical report is based on a dissertation submitted November 2020 by the author for the degree of Doctor of Philosophy to the University of Cambridge, Selwyn College. Technical reports published by the University of Cambridge Computer Laboratory are freely available via the Internet: https://www.cl.cam.ac.uk/techreports/ ISSN 1476-2986 Inline and Sideline Approaches for Low-cost Memory Safety in C Myoung Jin Nam System languages such as C or C++ are widely used for their high performance, however the allowance of arbitrary pointer arithmetic and typecast introduces a risk of memory corruptions. These memory errors cause unexpected termination of pro- grams, or even worse, attackers can exploit them to alter the behavior of programs or leak crucial data. Despite advances in memory safety solutions, high and unpredictable overhead remains a major challenge. Accepting that it is extremely difficult to achieve com- plete memory safety with the performance level suitable for production deployment, researchers attempt to strike a balance between performance, detection coverage, in- teroperability, precision, and detection timing. Some properties are much more desir- able, e.g. the interoperability with pre-compiled libraries. Comparatively less critical properties are sacrificed for performance, for example, tolerating longer detection de- lay or narrowing down detection coverage by performing approximate or probabilistic checking or detecting only certain errors.
    [Show full text]
  • Linux Core-Api Documentation
    Linux Core-api Documentation The kernel development community Jul 14, 2020 CONTENTS i ii Linux Core-api Documentation This is the beginning of a manual for core kernel APIs. The conversion (and writ- ing!) of documents for this manual is much appreciated! CONTENTS 1 Linux Core-api Documentation 2 CONTENTS CHAPTER ONE CORE UTILITIES This section has general and “core core”documentation. The first is a massive grab-bag of kerneldoc info left over from the docbook days; it should really be broken up someday when somebody finds the energy to do it. 1.1 The Linux Kernel API 1.1.1 List Management Functions void INIT_LIST_HEAD(struct list_head * list) Initialize a list_head structure Parameters struct list_head * list list_head structure to be initialized. Description Initializes the list_head to point to itself. If it is a list header, the result is an empty list. void list_add(struct list_head * new, struct list_head * head) add a new entry Parameters struct list_head * new new entry to be added struct list_head * head list head to add it after Description Insert a new entry after the specified head. This is good for implementing stacks. void list_add_tail(struct list_head * new, struct list_head * head) add a new entry Parameters struct list_head * new new entry to be added struct list_head * head list head to add it before Description 3 Linux Core-api Documentation Insert a new entry before the specified head. This is useful for implementing queues. void list_del(struct list_head * entry) deletes entry from list. Parameters struct list_head * entry the element to delete from the list. Note list_empty() on entry does not return true after this, the entry is in an undefined state.
    [Show full text]
  • Baggy Bounds Checking: an Efficient and Backwards-Compatible Defense Against Out-Of-Bounds Errors
    Baggy Bounds Checking: An Efficient and Backwards-Compatible Defense against Out-of-Bounds Errors � � Periklis Akritidis, Manuel Costa,† Miguel Castro,† Steven Hand � Computer Laboratory †Microsoft Research University of Cambridge, UK Cambridge, UK {pa280,smh22}@cl.cam.ac.uk {manuelc,mcastro}@microsoft.com Abstract Attacks that exploit out-of-bounds errors in C and C++ programs are still prevalent despite many years of re- search on bounds checking. Previous backwards compat- ible bounds checking techniques, which can be applied to unmodified C and C++ programs, maintain a data struc- ture with the bounds for each allocated object and per- form lookups in this data structure to check if pointers remain within bounds. This data structure can grow large and the lookups are expensive. In this paper we present a backwards compatible bounds Figure 1: Allocated memory is often padded to a partic- checking technique that substantially reduces perfor- ular alignment boundary, and hence can be larger than mance overhead. The key insight is to constrain the sizes the requested object size. By checking allocation bounds rather than object bounds, we allow benign accesses to the of allocated memory regions and their alignment to en- padding, but can significantly reduce the cost of bounds able efficient bounds lookups and hence efficient bounds lookups at runtime. checks at runtime. Our technique has low overhead in practice—only 8% throughput decrease for Apache— and is more than two times faster than the fastest pre- cause looking up bounds is expensive and the data struc- vious technique and about five times faster—using less ture can grow large.
    [Show full text]
  • Architecture-Independent Dynamic Information Flow Tracking
    ARCHITECTURE-INDEPENDENT DYNAMIC INFORMATION FLOW TRACKING A Thesis Presented by Ryan Whelan to The Department of Electrical and Computer Engineering in partial fulfillment of the requirements for the degree of Master of Science in Electrical and Computer Engineering Northeastern University Boston, Massachusetts November 2012 c Copyright 2012 by Ryan Whelan All Rights Reserved ii Abstract Dynamic information flow tracking is a well-known dynamic software analysis tech- nique with a wide variety of applications that range from making systems more secure, to helping developers and analysts better understand the code that systems are ex- ecuting. Traditionally, the fine-grained analysis capabilities that are desired for the class of these systems which operate at the binary level require that these analyses are tightly coupled to a specific ISA. This fact places a heavy burden on developers of these systems since significant domain knowledge is required to support each ISA, and our ability to amortize the effort expended on one ISA implementation cannot be leveraged to support the next ISA. Further, the correctness of the system must carefully evaluated for each new ISA. In this thesis, we present a general approach to information flow tracking that allows us to support multiple ISAs without mastering the intricate details of each ISA we support, and without extensive verification. Our approach leverages bi- nary translation to an intermediate representation where we have developed detailed, architecture-neutral information flow models. To support advanced instructions that are typically implemented in C code in binary translators, we also present a combined static/dynamic analysis that allows us to accurately and automatically support these instructions.
    [Show full text]
  • Cornucopia: Temporal Safety for CHERI Heaps
    Cornucopia: Temporal Safety for CHERI Heaps Nathaniel Wesley Filardo,∗ Brett F. Gutstein,∗ Jonathan Woodruff,∗ Sam Ainsworth,∗ Lucian Paul-Trifu,∗ Brooks Davis,y Hongyan Xia,∗ Edward Tomasz Napierala,∗ Alexander Richardson,∗ John Baldwin,z David Chisnall,x Jessica Clarke,∗ Khilan Gudka,∗ Alexandre Joannou,∗ A. Theodore Markettos,∗ Alfredo Mazzinghi,∗ Robert M. Norton,∗ Michael Roe,∗ Peter Sewell,∗ Stacey Son,∗ Timothy M. Jones,∗ Simon W. Moore,∗ Peter G. Neumann,y Robert N. M. Watson∗ ∗University of Cambridge, Cambridge, UK; ySRI International, Menlo Park, CA, USA; xMicrosoft Research, Cambridge, UK; zArarat River Consulting, Walnut Creek, CA, USA Abstract—Use-after-free violations of temporal memory safety While use-after-free heap vulnerabilities are ultimately due continue to plague software systems, underpinning many high- to application misuse of the malloc() and free() interface, impact exploits. The CHERI capability system shows great complete sanitization of the vast legacy C code base, or even promise in achieving C and C++ language spatial memory safety, preventing out-of-bounds accesses. Enforcing language-level tem- of highly maintained security-critical programs, has proved poral safety on CHERI requires capability revocation, traditionally infeasible. Instead, we turn our attention to the allocator achieved either via table lookups (avoided for performance in itself, and seek to robustly mitigate temporal-safety bugs. the CHERI design) or by identifying capabilities in memory to Many attempts have been made to mitigate temporal-safety revoke them (similar to a garbage-collector sweep). CHERIvoke, vulnerabilities in existing architectures (discussed in §IX), and a prior feasibility study, suggested that CHERI’s tagged capa- bilities could make this latter strategy viable, but modeled only they have demonstrated that temporal safety is not possible for architectural limits and did not consider the full implementation today’s computers without overheads above 5%, a threshold that or evaluation of the approach.
    [Show full text]
  • MESH: a Memory-Efficient Safe Heap for C/C++
    MESH: A Memory-Efficient Safe Heap for C/C++ Emanuel Q. Vintila Philipp Zieris Julian Horsch [email protected] [email protected] [email protected] Fraunhofer AISEC Fraunhofer AISEC Fraunhofer AISEC Garching, near Munich, Germany Garching, near Munich, Germany Garching, near Munich, Germany ABSTRACT 1 INTRODUCTION While memory corruption bugs stemming from the use of unsafe The C and C++ programming languages are preferred for system programming languages are an old and well-researched problem, programming because they are efficient and offer low-level control. the resulting vulnerabilities still dominate real-world exploitation These advantages come at the cost of memory safety, requiring the today. Various mitigations have been proposed to alleviate the programmer to manually manage heap memory and ensure the problem, mainly in the form of language dialects, static program legality of memory accesses. Incorrect handling by the programmer analysis, and code or binary instrumentation. Solutions like Adress- can lead to serious issues [43] such as buffer overflows or use-after- Sanitizer (ASan) and Softbound/CETS have proven that the latter free bugs, which can be exploited by attackers to hijack the control- approach is very promising, being able to achieve memory safety flow (causing the program to inadvertently change its course of without requiring manual source code adaptions, albeit suffering execution) [6, 11, 35, 39] or to leak information [18, 40]. Even though substantial performance and memory overheads. While perfor- memory vulnerabilities are long-known issues, they are still very mance overhead can be seen as a flexible constraint, extensive common in mainstream programs: Out of all the vulnerabilities memory overheads can be prohibitive for the use of such solutions reported in the Common Vulnerabilities and Exposures (CVE) data- in memory-constrained environments.
    [Show full text]
  • Real-World Buffer Overflow Protection for Userspace & Kernelspace
    Real-World Buffer Overflow Protection for Userspace & Kernelspace Michael Dalton, Hari Kannan, Christos Kozyrakis Computer Systems Laboratory Stanford University {mwdalton, hkannan, kozyraki}@stanford.edu Abstract Despite decades of research, the available buffer over- Despite having been around for more than 25 years, flow protection mechanisms are partial at best. These buffer overflow attacks are still a major security threat for mechanisms provide protection only in limited situa- deployed software. Existing techniques for buffer over- tions [9], require source code access [51], cause false flow detection provide partial protection at best as they positives in real-world programs [28, 34], can be de- detect limited cases, suffer from many false positives, re- feated by brute force [44], or result in high runtime over- quire source code access, or introduce large performance heads [29]. Additionally, there is no practical mechanism overheads. Moreover, none of these techniques are easily to protect the OS kernel from buffer overflows or unsafe applicable to the operating system kernel. user pointer dereferences. This paper presents a practical security environment Recent research has established dynamic information for buffer overflow detection in userspace and ker- flow tracking (DIFT) as a promising platform for detect- nelspace code. Our techniques build upon dynamic in- ing a wide range of security attacks on unmodified bina- formation flow tracking (DIFT) and prevent the attacker ries. The idea behind DIFT is to tag (taint) untrusted data from overwriting pointers in the application or operat- and track its propagation through the system. DIFT as- ing system. Unlike previous work, our technique does sociates a tag with every memory location in the system.
    [Show full text]
  • Analysis of Defenses Against Code Reuse Attacks on Modern and New
    Analysis of Defenses Against Code Reuse Attacks on Modern and New Architectures by Isaac Noah Evans Submitted to the Department of Electrical Engineering and Computer Science in partial fulfillment of the requirements for the degree of Master of Engineering in Electrical Engineering and Computer Science at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY September 2015 ○c Massachusetts Institute of Technology 2015. All rights reserved. The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part in any medium now known or hereafter created. Author................................................................ Department of Electrical Engineering and Computer Science September 2015 Certified by. Dr. Hamed Okhravi Technical Staff, MIT Lincoln Laboratory Thesis Supervisor Certified by. Dr. Howard Shrobe Principal Research Scientist and Director of Security, CSAIL Thesis Supervisor Accepted by . Dr. Christopher J. Terman Chairman, Masters of Engineering Thesis Committee 2 Analysis of Defenses Against Code Reuse Attacks on Modern and New Architectures by Isaac Noah Evans Submitted to the Department of Electrical Engineering and Computer Science on September 2015, in partial fulfillment of the requirements for the degree of Master of Engineering in Electrical Engineering and Computer Science Abstract Today, the most common avenue for exploitation of computer systems is a control-flow attack in which the attacker gains direct or indirect control of the instruction pointer. In order to gain remote code execution, attackers then exploit legitimate fragments of code in the executable via techniques such as return-oriented-programming or virtual table overwrites. This project aims to answer fundamental questions about the efficacy of control- flow-integrity (CFI), a defensive technique which attempts to prevent such attacks by ensuring that every control flow transfer corresponds to the original intent ofthe program author.
    [Show full text]