RealPlayer is an application for playing various media formats,
developed by RealNetworks Inc. For more information, visit
Remote exploitation of a heap-based buffer overflow vulnerability in the
RealText file format parser within various versions of RealNetworks
Inc.'s RealPlayer could allow attackers to execute arbitrary code.
The vulnerability specifically exists because of a string copying
operating into a fixed size heap buffer using the sprintf function. The
following function from /datatype/text/realtext/fileformat/rtffplin.cpp
is the offending code:
const char* pFilename = "[rt file]";
pTmp = new char;
sprintf(pTmp, /* Flawfinder: ignore */
"Version in "%s" is not recognized installed"
" RealText file format",pFilename);
0, (const char*) pTmp, NULL);
delete  pTmp;
The variable pTmp points to 256 bytes of space on the heap. pFilename is
a string pointer that points to data supplied in the RealText stream.
When the sprintf is executed, the data is copied into the 256 byte heap
buffer without any length checking, thus allowing a heap overflow to
occur. Once the heap is overflown, an attacker can eventually write to
arbitrary locations in memory, allowing for the execution of arbitrary
Exploitation allows for arbitrary code execution as the user who opened
the RealMedia file.
Exploitation requires an attacker to craft a malicious RealMedia file
that uses RealText and convince a user to open it. An attacker could
also force a web browser to refresh and automatically load the RealMedia
file from a normal web page under the attacker's control. In default
installations of RealPlayer under Windows XP, Internet Explorer will not
prompt the user for an action when encountering most RealMedia files. It
will open the file without delay, thus providing an effective method of
iDEFENSE Labs has confirmed that RealNetworks' RealPlayer 10.5
220.127.116.116 on Windows and RealPlayer 10 and 10.0.1.436 on Linux are
vulnerable. It is suspected that previous versions of RealPlayer are
also vulnerable. It is also suspected that RealOne player is vulnerable.
Although there is no way to completely protect yourself from this
vulnerability, aside from removing the RealPlayer software, the
following actions may be taken to minimize risk for automated
Disable ActiveX controls and plugins, if not necessary for daily
operations, using the following steps:
1. In IE, click on Tools and select Internet Options from the drop-down
2. Click the Security tab and the Custom Level button.
3. Under ActiveX Controls and Plugins, then Run Activex Controls and
Plugins, click the Disable radio button.
The vendor has addressed this issue in the following security advisory:
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-1766 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
04/26/2005 Initial vendor notification
04/26/2005 Initial vendor response
06/23/2005 Coordinated public disclosure
The discoverer of this vulnerability wishes to remain anonymous.
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Copyright © 2005 Verisign, Inc.
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