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                             Luigi Auriemma

Application:  PeerCast
              http://www.peercast.org
Versions:     <= 0.1217 and SVN <= 344
Platforms:    Windows, plugin for Winamp, Linux and Mac
Bug:          heap overflow
Exploitation: remote
Date:         17 Dec 2007
Author:       Luigi Auriemma
              e-mail: aluigi@autistici.org
              web:    aluigi.org


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1) Introduction
2) Bug
3) The Code
4) Fix


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===============
1) Introduction
===============


PeerCast is a multi platform open source software for peer2peer radio
streaming.
The broadcasters are visible at http://yp.peercast.org


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======
2) Bug
======


The handshakeHTTP function which handles all the requests received by
the other clients is vulnerable to a heap overflow which allows an
attacker to fill the loginPassword and loginMount buffers located in
the Servent class with how much data he wants.

>From servhs.cpp:

void Servent::handshakeHTTP(HTTP &http, bool isHTTP)
{
    char *in = http.cmdLine;
    ...
    }else if (http.isRequest("SOURCE"))
    {
        if (!isAllowed(ALLOW_BROADCAST))
        ...
            mount = in+strlen(in);
            while (*--mount)
                if (*mount == '/')
                {
                    mount[-1] = 0; // password preceeds
                    break;
                }
            strcpy(loginPassword,in+7);
        ..
        if (mount)
            strcpy(loginMount,mount);
            ...

ALLOW_BROADCAST ("allowBroadcast" in peercast.ini) is enabled by
default.


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===========
3) The Code
===========


http://aluigi.org/poc/peercasthof.zip


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======
4) Fix
======


Version 0.1218 or SVN 347


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--- 
Luigi Auriemma
http://aluigi.org