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Qualifying Event Style Sample Challenge - TNETS_00002

Original Versions

Known Vulnerabilities

  • CWE-122 - Heap-based Buffer Overflow

Author Information

"Jason L. Wright"

DARPA performer group

Thought Networks (TNETS)


Virtual pet ownership.

Feature List

This services allows the user to create virtual pets and have them perform a few rudimentary tricks. When a pet becomes too annoying, it can be deleted.


Normally a pet is given a name right after it is created and never renamed. However, there's a bug in this program: when you rename a pet it appends to the current name. An annoyance to be sure, but worse, it allows for spilling into an adjacent C++ vtable.

To make life easier for the programmer (not the user), a "debug" trick can be performed which displays the address of each of the pet's "this" pointer.

Generic class of vulnerability

Heap-based Buffer Overflow

CWE classification

CWE-122: Heap based Buffer Overflow


This CB is primarily provided to demonstrate the use of C++ as a challenge binary language. Several language features are used (static constructors/ destructors, virtual functions, overloading, etc.). Several features are explicitly not used: runtime type information (RTTI) and exceptions.

Future versions of this CB may use RTTI (it's not that hard to implement), but exceptions look painful (though libcgc.a now has setjmp/longjmp...).

The overflow is easy enough to create: it requires reasoning about the protocol and realizing that additional names for a pet are blindly concatenated with the existing name. To get an exploit working, a valid vtable must be constructed. The "debug" trick leaks the value of the "this" pointer for each pet (this cuts out reasoning about the "new operator"'s implementation.

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