200511-asterisk.txt

`Assurance.com.au - Vulnerability Advisory  
-----------------------------------------------  
Release Date:  
07-Nov-2005  
  
Software:  
Asterisk Web-VoiceMail (Comedian VoiceMail)  
http://www.asterisk.org/  
  
Asterisk is a complete PBX in software. It runs on Linux, BSD and MacOSX and   
provides all of the features you would expect from a PBX and more.   
Asterisk does voice over IP in many protocols, and can interoperate with almost  
all standards-based telephony equipment using relatively inexpensive hardware.  
  
Versions affected:  
Asterisk Versions <= 1.0.9  
Asterisk Beta Versions <= 1.2.0-beta1  
Asterisk @ Home Versions <= 1.5  
Asterisk @ Home Beta Versions <= 2.0 Beta 4   
  
  
Vulnerability discovered:  
  
A vulnerability in the voicemail retrieval system allows an authenticated  
user to download any .wav/.WAV file from the system, including other  
users voicemail messages.  
  
Vulnerability impact:  
  
Low - Insecure web-ui causes breach of privacy  
  
Vulnerability information  
  
vmail.cgi doesn't clean a parameter passed by the web user which is  
later used to open a file and return a raw stream to the user.  
This allows any authenticated user of the voicemail system to listen to  
other peoples messages, or to open any file with the extension .wav/.WAV  
on the system.  
  
Example:  
http://asterisk.example.org/cgi-bin/vmail.cgi?action=audio& \  
folder=../201/INBOX&mailbox=200&context=default&password=12345 \  
&msgid=0001&format=wav  
  
This will return /var/spool/asterisk/voicemail/default/201/INBOX/msg0001.wav  
when logged in as the 'extension 200' user.  
  
Solution:  
Asterisk has released patches for the vulnerabilities.  
Ensure you are running Asterisk versions > 1.0.9 / 1.2.0-beta1  
Ensure you are running Asterisk @ Home versions > 1.5 / 2.0 beta 4  
  
References:  
Assurance.com.au advisory  
http://www.assurance.com.au/advisories/200511-asterisk.txt  
  
Asterisk advisory note  
http://www.asterisk.org/changelog  
  
Credit:  
Adam Pointon of Assurance.com.au  
http://www.assurance.com.au/  
  
Disclosure timeline:  
17-Oct-2005 - Discovered during a quick audit of the asterisk web ui  
18-Oct-2005 - Email sent to support and the primary author  
18-Oct-2005 - Immediate response received  
31-Oct-2005 - Patched version committed to CVS  
07-Nov-2005 - Advisory released  
  
About us:  
Assurance.com.au is a specialised information security consultancy.  
Our mission is to help organisations identify and secure their information  
assets. Our expertise concentrates in security architecture design,  
managed security and professional services in security testing/review  
and compliance.  
  
Supporting this approach are professional and managed services in the  
following areas:  
  
* Compliance Services - Penetration testing, security reviews,   
compliance and audit services  
* Wireless and mobility solutions - design, installation and management  
of IEEE 802.11a/b/g (WiFi), tele-mobility and other wireless solutions  
* UNIX-like systems, network and security advice and consulting  
  
Assurance.com.au also provides organisations with services to support  
compliance to legislative, public and internal/private standards. While  
primarily specialising in Australian & New Zealand standards efforts  
Assurance.com.au also works with other international standards related  
to information security  
  
These include:  
* ISO/IEC 17799:*, AS/NZS 17799:*, BS7799  
* ISO 15408 (Common Criteria), ITSEC, TCSEC  
* ISO 13569, ISO 11131  
* ACSI33, AS2805, AS3806, AS4360, AS4539, AS8018, HB231:2001, NPP4 (privacy)  
* Sarbanes-Oxley  
  
  
  
  
`