What is buffer overflow in java

Buffer Overflows and Java?!

A buffer overflow vulnerability exists in the Yamaha MidiPlug that can be accessed via a Text variable found in an EMBED tag.

* Attack Example: Overflow Variables and Tags in Exim A buffer overflow in Exim allows local users to gain root privileges by providing a long :include: option in a .forward file. • Table of Contents • Index Exploiting Software How to Break Code Attack Pattern: Overflow Symbolic Links By Greg Hoglund , Gary McGraw A user often has direct control over symbolic links. A symbolic link can Publisher: Addison Wesley occasionally provide access to a file that might otherwise be out of bounds. Pub Date: February 17, 2004 Symbolic links provide similar avenues of attack as configuration files, although ISBN: 0-201-78695-8 they are one level of indirection away. Remember that the target software will consume Pages: the 512 data pointed to by the link file and sometimes use it to set variables. This often leads to an unchecked buffer. * How Attack does software Example: br ak? Overflow How do attackers with Symbolic make s ftware Links break in on EFTP purpose? Server Why are firewalls, intrusion detection systems, and antivirus software not keeping out the bad guys? What tools can be used to break software? This book provides the answers. The EFTP server has a buffer overflow that can be exploited if an attacker uploads a .lnk (link) file that contains more than 1,744 bytes. This is a classic example of an indirect buffer Exploiting Software is loaded with examples of real attacks, attack patterns, tools, and overflow. First the attacker uploads some content (the link file) and then the attacker causes techniques used by bad guys to break software. If you want to protect your software from the client consuming the data to be exploited. In this example, the ls command is exploited attack, you must first learn how real attacks are really carried out. to compromise the server software. This must-have book may shock you—and it will certainly educate you.Getting beyond the script kiddie treatment found in many hacking books, you will learn about Attack Why software Pattern: exploit MIME will Conversion continue to be a serious problem When network security mechanisms do not work The MIME system is designed to allow various different information formats to be interpreted and sent via e-mail. Attack points exist when data are converted to Attack patterns MIME-compatible format and back. Reverse engineering Classic attacks against server software * Attack Example: Sendmail Overflow Surprising attacks against client software A MIME conversion buffer overflow exists in Sendmail versions 8.8.3 and 8.8.4. Techniques for crafting malicious input The technical details of buffer overflows Rootkits Attack Pattern: HTTP Cookies Exploiting Software is filled with the tools, concepts, and knowledge necessary to break software. Because HTTP is a stateless protocol, cookies (small files that are stored in a client browser) were invented, mostly to preserve state. Poor design of cookie handling systems leaves both clients and HTTP daemons susceptible to buffer overflow attack.

The Apache HTTPD is the most popular Web server in the world. HTTPD has built-in mechanisms to handle cookies. Versions 1.1.1 and earlier suffer from a cookie-induced buffer overflow. All of these examples are just the tip of the iceberg. Client software programs are almost never well tested, let alone tested explicitly for security. One particularly interesting aspect of client-side exploits is that the exploit code ends up executing with whatever permissions the

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user has. This means the code ends up with access to everything the user has access
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to—including interesting things like e-mail and confidential data. Exploiting Software How to Break Code Many of these attacks are particularly potent, especially when they are used in concert with By Greg Hoglund , Gary McGraw social engineering. If, as an attacker, you can get somebody to open a file, you can usually install a rootkit. Of course, because of the up-close and personal nature of opening a file, Publisher: Addison Wesley attack code needs to be stealthy to remain undetected. Pub Date: February 17, 2004 ISBN: 0-201-78695-8 Pages: 512 How does software break? How do attackers make software break on purpose? Why are firewalls, intrusion detection systems, and antivirus software not keeping out the bad guys? What tools can be used to break software? This book provides the answers. Exploiting Software is loaded with examples of real attacks, attack patterns, tools, and techniques used by bad guys to break software. If you want to protect your software from attack, you must first learn how real attacks are really carried out. This must-have book may shock you—and it will certainly educate you.Getting beyond the script kiddie treatment found in many hacking books, you will learn about Why software exploit will continue to be a serious problem When network security mechanisms do not work Attack patterns Reverse engineering Classic attacks against server software Surprising attacks against client software Techniques for crafting malicious input The technical details of buffer overflows Rootkits Exploiting Software is filled with the tools, concepts, and knowledge necessary to break software.

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What is buffer overflow in Java?

A buffer overflow occurs when data is written beyond the boundaries of a fixed length buffer overwriting adjacent memory locations which may include other buffers, variables, and program flow data.

Is buffer overflow attack possible in Java?

Since Java Strings are based on char arrays and Java automatically checks array bounds, buffer overflows are only possible in unusual scenarios: If you call native code via JNI. In the JVM itself (usually written in C++) The interpreter or JIT compiler does not work correctly (Java bytecode mandated bounds checks)

What is buffer overflow attack with example?

Attackers exploit buffer overflow issues by overwriting the memory of an application. For example, an attacker can overwrite a pointer (an object that points to another area in memory) and point it to an exploit payload, to gain control over the program.

What is meant by buffer overflow?

A buffer overflow, or buffer overrun, occurs when more data is put into a fixed-length buffer than the buffer can handle. This overflow usually results in a system crash, but it also creates the opportunity for an attacker to run arbitrary code or manipulate the coding errors to prompt malicious actions.

How does buffer overflow attacks work?

What is buffer overflow vulnerability?

How does buffer overflow work exactly?

What does buffer overflow mean?

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Does Java have buffer overflows?

Does Java have buffer overflows? If yes can you give me scenarios?

Java Solutions

Solution 1 — Java

Since Java Strings are based on char arrays and Java automatically checks array bounds, buffer overflows are only possible in unusual scenarios:

1. If you call native code via JNI
2. In the JVM itself (usually written in C++)
3. The interpreter or JIT compiler does not work correctly (Java bytecode mandated bounds checks)

Solution 2 — Java

Managed languages such as Java and C# do not have these problems, but the specific virtual machines (JVM/CLR/etc) which actually run the code may.

Solution 3 — Java

For all intents and purposes, no.

Java has array bounds checking which will check that data cannot be accessed from area outside of the allocated array. When one tries to access area that is beyond the size of the array, an ArrayOutOfBounds exception will be thrown.

If there is a buffer-overrun, it is probably from a bug in the Java Virtual Machine, and is, to my knowledge, not the intended behavior that is written in the Java Language Specifications nor the Java Virtual Machine Specifications.

Solution 4 — Java

Yes and no. No, in that you cannot really create mistakenly open yourself up to a buffer overflow vulnerability because it is a managed memory model. However, there can be buffer overflow vulnerabilities in the JVM and JDK. See this Secunia advisory:

Or see these old advisories on several previous JDK and JRE vulnerabilities:

• Integer and Buffer Overflow Vulnerabilities in the Java Runtime Environment (JRE) «unpack200» JAR Unpacking Utility May Lead to Escalation of Privileges https://download.oracle.com/sunalerts/1020225.1.html

> Integer and buffer overflow vulnerabilities in the Java Runtime > Environment (JRE) with unpacking applets and Java Web Start > applications using the «unpack200» JAR unpacking utility may allow an > untrusted applet or application to escalate privileges. For example, > an untrusted applet may grant itself permissions to read and write > local files or execute local applications that are accessible to the > user running the untrusted applet. > > Sun acknowledges with thanks, «regenrecht» working with the iDefense > VCP (http://labs.idefense.com/vcp/) and Chris Evans of Google for > bringing these issues to our attention.

• Multiple vulnerabilities have been identified in Sun Java Development Kit (JDK) and Java Runtime Environment (JRE). https://security.gentoo.org/glsa/200705-23

> An unspecified vulnerability involving an «incorrect use of system > classes» was reported by the Fujitsu security team. Additionally, > Chris Evans from the Google Security Team reported an integer overflow > resulting in a buffer overflow in the ICC parser used with JPG or BMP > files, and an incorrect open() call to /dev/tty when processing > certain BMP files.

Solution 5 — Java

A buffer overflow in the strict sense of overwriting the stack or heap itself would require either:

1. A bug in the framework (these have existed in the past and may well again)
2. The use of JNI (essentially no longer using managed code)

A buffer overflow in the sense that you have code using a buffer and your code is responsible for parsing it correctly but fail to do so is possible. For example You might write an XML parser and someone could provide you with a malformed (or legitimate but uncommon) request which, owing to the design of your parser overwrites previously validated data with some payload that would cause your application to behave badly.

This latter form is less likely but a poorly written sql string cleansing function widely distributed that had a problem such as this would be an inviting target.

Solution 6 — Java

Java (and .Net) virtual machines catch code that tries to write outside of reserved memory. Applications that don’t handle this correctly can still cause security problems. If malicious users can trigger exceptions by entering invalid input they can do denial of service attacks for example.

Solution 7 — Java

As has already been pointed out, Java has, as a language, bounds checking on all memory access, and if there’s an error here, the JVM is at fault and not the program. However, what should be noted, which is a similar argument to memory leaks in Java; while not possible to smash the stack, an ArrayOutOfBoundsException in the wrong place, which is not handled correctly, may still end up screwing up your system.

Solution 8 — Java

You could conceivably cause a buffer overflow in a Java program if you were using the Java Native Interace (JNI) facility to invoke external code, and the external code had an exploitable issue. This is fairly uncommon, as most applications avoid using JNI where possible.

Solution 9 — Java

It is possible for a method to write into valid entries of an array that it did not intend to, typically through integer overflow.

For instance the following is not sufficient to check bounds:

/* !! WRONG !! */ 0 0 len && off+len /* !! WRONG !! */ 

IIRC, StringBuffer once had a bug like that, but there wasn’t anything interesting you could do with it.

Solution 10 — Java

One of the key features of JAVA is Security. Programs written in interpreted languages are not prone to the buffer overflow exploit, but you can always cause a buffer overflow in Interpreter itself. Although it will be difficult. Similarly Python also is an interpreted language and is safe from buffer overflow.

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