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Category:   Application (Multimedia)  >   RealOne (RealPlayer) Vendors:   RealNetworks
RealPlayer SMIL parseWallClockValue() Stack Overflow Lets Remote Users Execute Arbitrary Code
SecurityTracker Alert ID:  1018299
SecurityTracker URL:
CVE Reference:   CVE-2007-3410   (Links to External Site)
Date:  Jun 26 2007
Impact:   Execution of arbitrary code via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 10.5-GOLD; possibly other versions
Description:   A vulnerability was reported in RealPlayer. A remote user can cause arbitrary code to be executed on the target user's system.

A remote user can create a SMIL file with a specially crafted time value that, when loaded by the target user, will trigger a stack overflow in the SmilTimeValue::parseWallClockValue() function and execute arbitrary code on the target system. The code will run with the privileges of the target user.

The vendor was notified on October 2, 2006.

iDefense reported this vulnerability.

Impact:   A remote user can create a file that, when loaded by the target user, will execute arbitrary code on the target user's system.
Solution:   The vendor has issued a fix.

A vendor advisory was not available at the time of this entry.

[Editor's note: It is not clear in which version the fix was introduced.]

Vendor URL: (Links to External Site)
Cause:   Boundary error
Underlying OS:  Windows (Any)

Message History:   This archive entry has one or more follow-up message(s) listed below.
Aug 17 2007 (Red Hat Issues Fix) RealPlayer SMIL parseWallClockValue() Stack Overflow Lets Remote Users Execute Arbitrary Code
Red Hat has released a fix for Red Hat Enterprise Linux Extras 3, 4, and 5.

 Source Message Contents

Subject:  iDefense Security Advisory 06.26.07: RealNetworks

RealNetworks RealPlayer/HelixPlayer SMIL wallclock Stack Overflow

iDefense Security Advisory 06.26.07
Jun 26, 2007


RealPlayer is an application for playing various media formats,
developed by RealNetworks Inc. HelixPlayer is the open source version
of RealPlayer. More information can be found at the URLs shown below.

Synchronized Multimedia Integration Language (SMIL) is a markup language
used to specify the use of several multi-media concepts when rendering
media. Some such concepts are timing, transitions, and embedding. More
information is available from WikiPedia at the following URL.


Remote exploitation of a buffer overflow within RealNetworks' RealPlayer
and HelixPlayer allows attackers to execute arbitrary code in the context
of the user.

The issue specifically exists in the handling of HH:mm:ss.f time formats
by the 'wallclock' functionality within the code supporting SMIL2. An
excerpt from the code follows.

   924    HX_RESULT
   925    SmilTimeValue::parseWallClockValue(REF(const char*) pCh)
   926    {
   957        char buf[10]; /* Flawfinder: ignore */
   962        while (*pCh)
   963        {
   972             else if (isspace(*pCh) || *pCh == '+' || *pCh == '-'
|| *pCh == 'Z')
   973             {
   974                 // this will find the last +, - or Z... which is
what we want.
   975                 pTimeZone = pCh;
   976             }
   982             ++pCh;
   983        }
  1101        if (pTimePos)
  1102        {
  1103        //HH:MM...
  1133          if (*(pos-1) == ':')
  1134          {
  1148            if (*(pos-1) == '.')
  1149            {
  1150            // find end.
  1151            UINT32 len = 0;
  1152            if (pTimeZone)
  1153            {
  1154                len = pTimeZone - pos;
  1155            }
  1156            else
  1157            {
  1158                len = end - pos;
  1159            }
  1160            strncpy(buf, pos, len); /* Flawfinder: ignore */

The stack buffer is declared to be 10 bytes on line 957. You can see
that it has a comment which will cause the FlawFinder program to ignore
this buffer.

The loop, which begins on line 962, runs through the parameter to the
function looking for characters that denote different sections of the
time format. When it encounters white space, or the +, -, or Z
characters it will record the location for later use. If a time was
located and it contains both a colon and a period the vulnerable code
will be reached.

The length of data to copy into the stack buffer is calculated either on
line 1154 or line 1158 depending on whether or not a timezone is present.
Neither calculations take into consideration the constant length of the
'buf' buffer and therefore a stack-based buffer overflow can occur on
line 1160. Again, notice that this unsafe use of strncpy() is also
marked with a FlawFinder ignore comment.


Exploitation requires that an attacker persuade a user to supply
RealPlayer or HelixPlayer with a maliciously crafted SMIL file. For
example, this can be accomplished by convincing them to visit a
malicious web page.

The data that is used to overflow the buffer is quite limited in the
range of characters that are allowed. However, given the ease of
address space manipulation within web browsers, exploitation is not
substantially impacted by this limitation.

The RealPlayer plug-in can be referenced within a web browser by using


iDefense has confirmed the existence of this vulnerability in version
10.5-GOLD of RealNetworks' RealPlayer and HelixPlayer. Confirmation of
the existence this vulnerability within HelixPlayer was done via source
code review. Older versions are assumed to be vulnerable.


For Windows systems, setting the kill-bit for the associated CLSID,
despite greatly reducing the media player's functionality, will
mitigate exploitation. It should be noted that the CLSID listed may not
be the only CLSID allowing access to the vulnerable code.


RealNetworks has addressed this vulnerability by releasing fixed
versions of their software.

RealNetworks has not provided iDefense with any links referring to
updated packages or advisories. Installing the latest version from
their web site will address the vulnerability.


The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-3410 to this issue. This is a candidate for inclusion in
the CVE list (, which standardizes names for
security problems.


10/02/2006  Initial vendor notification
10/03/2006  Initial vendor response
06/26/2007  Public disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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