Worm containment must be automatic because worms can spread too fast for humans to respond. Recent work proposed network-level techniques to automate worm containment; these techniques have limitations because there is no information about the vulnerabilities exploited by worms at the network level. We propose Vigilante, a new end-to-end architecture to contain worms automatically that addresses these limitations. In Vigilante, hosts detect worms by instrumenting vulnerable programs to analyze infection attempts. We introduce dynamic data-flow analysis: a broad-coverage host-based algorithm that can detect unknown worms by tracking the flow of data from network messages and disallowing unsafe uses of this data. We also show how to integrate other host-based detection mechanisms into the Vigilante architecture. Upon detection, hosts generate self-certifying alerts (SCAs), a new type of security alert that can be inexpensively verified by any vulnerable host. Using SCAs, hosts can cooperate to contain an outbreak, without having to trust each other. Vigilante broadcasts SCAs over an overlay network that propagates alerts rapidly and resiliently. Hosts receiving an SCA protect themselves by generating filters with vulnerability condition slicing: an algorithm that performs dynamic analysis of the vulnerable program to identify control-flow conditions that lead

Applications written in unsafe languages like C and C++ are vulnerable to memory errors such as buffer overflows, dangling pointers, and reads of uninitialized data. Such errors can lead to program crashes, security vulnerabilities, and unpredictable behavior. We present DieHard, a runtime system that tolerates these errors while probabilistically maintaining soundness. DieHard uses randomization and replication to achieve probabilistic memory safety by approximating an infinite-sized heap. DieHard’s memory manager randomizes the location of objects in a heap that is at least twice as large as required. This algorithm prevents heap corruption and provides a probabilistic guarantee of avoiding memory errors. For additional safety, DieHard can operate in a replicated mode where multiple replicas of the same application are run simultaneously. By initializing each replica with a different random seed and requiring agreement on output, the replicated version of Die-Hard increases the likelihood of correct execution because errors are unlikely to have the same effect across all replicas. We present analytical and experimental results that show DieHard’s resilience to a wide range of memory errors, including a heap-based buffer overflow in an actual application.

We propose a new approach for reacting to a wide variety of software failures, ranging from remotely exploitable vulnerabilities to more mundane bugs that cause abnormal program termination (e.g., illegal memory dereference). Our emphasis is in creating "self-healing" software that can protect itself against a recurring fault until a more comprehensive fix is applied.

IRON FILE SYSTEMSVijayan Prabhakaran Disk drives are widely used as a primary medium for storing information.While commodity file systems trust disks to either work or fail completely, modern disks exhibit complex failure modes such as latent sector faults and block corrup-tions, where only portions of a disk fail.

This paper presents a technique that uses code to automatically generate its own test cases at run-time by using a combination of symbolic and concrete (i.e., regular) execution. The input values to a program (or software component) provide the standard interface of any testing framework with the program it is testing, and generating input values that will explore all the “interesting” behavior in the tested program remains an important open problem in software testing research. Our approach works by turning the problem on its head: we lazily generate, from within the program itself, the input values to the program (and values derived from input values) as needed. We applied the technique to real code and found numerous corner-case errors ranging from simple memory overflows and infinite loops to subtle issues in the interpretation of language standards.

Many applications demand availability. Unfortunately, software failures greatly reduce system availability. Previous approaches for surviving software failures suffer from several limitations, including requiring application restructuring, failing to address deterministic software bugs, unsafely speculating on program execution, and re-quiring a long recovery time. This paper

Exploits for new vulnerabilities, especially when incorporated within a fast spreading worm, can compromise nearly all vulnerable hosts within a short amount of time. This problem demonstrates the need for fast defenses which can react to a new vulnerability quickly. In addition, a realistic defense system should (a) not require source code since in practice most vulnerable systems do not have source code access nor is there adequate time to involve the software vendor, (b) be accurate, i.e., have a negligible false positive rate and low false negative rate, and (c) be efficient, i.e., add little overhead to normal program execution.

Access control misconfigurations are widespread and can result in damaging breaches of confidentiality. This paper presents TightLip, a privacy management system that helps users define what data is sensitive and who is trusted to see it rather than forcing them to understand or predict how the interactions of their software packages can leak data. The key mechanism used by TightLip to detect and prevent breaches is the doppelganger process. Doppelgangers are sandboxed copy processes that inherit most, but not all, of the state of an original process. The operating system runs a doppelganger and its original in parallel and uses divergent process outputs to detect potential privacy leaks. Support for doppelgangers is compatible with legacy-code, requires minor modifications to existing operating systems, and imposes negligible overhead for common workloads. SpecWeb99 results show that Apache running on a TightLip prototype exhibits a 5 % slowdown in request rate and response time compared to an unmodified server environment. 1

We describe an ongoing project, the deployment of a modular checker to statically find and prevent every buffer overflow in future versions of a Microsoft product. Lightweight annotations specify requirements for safely using each buffer, and functions are checked individually to ensure they obey these requirements and do not overflow. To date over 400,000 annotations have been added to specify buffer usage in the source code for this product, of which over 150,000 were automatically inferred, and over 3,000 potential buffer overflows have been found and fixed. 1.

Buffer overflow vulnerabilities are caused by programming errors that allow an attacker to cause the program to write beyond the bounds of an allocated memory block to corrupt other data structures. The standard way to exploit a buffer overflow vulnerability involves a request that is too large for the buffer intended to hold it. The buffer overflow error causes the program to write part of the request beyond the bounds of the buffer, corrupting the address space of the program and causing the program to execute injected code contained in the request. We have implemented a compiler that inserts dynamic checks into the generated code to detect all out of bounds memory accesses. When it detects an out of bounds write, it stores the value away in a hash table to return as the value for corresponding out of bounds reads. The net effect is to (conceptually) give each allocated memory block unbounded size and to eliminate out of bounds accesses as a programming error. We have acquired several widely used open source servers (Apache, Sendmail, Pine, Mutt, and Midnight Commander). With standard compilers, all of these servers are vulnerable to buffer overflow attacks as documented at security tracking web sites. Our compiler eliminates these security vulnerabilities (as well as other memory errors). Our results show that our compiler enables the servers to execute successfully through buffer overflow attacks to continue to correctly service user requests without security vulnerabilities. 1.