Asterisk CallerID CDR SQL Injection

["@stake Advisories" <advisories () atstake com>]

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                             @stake, Inc.
                           www.atstake.com

                          Security Advisory

Advisory Name: Asterisk CallerID CDR SQL Injection
Release Date: 09/11/2003
 Application: Asterisk
    Platform: Linux (x86)
    Severity: An attacker is able to obtain remote access to the
              database/host via the CallerID string
     Authors: Ollie Whitehouse [ollie () atstake com]
Vendor Status: Informed / CVS Updated 9th of September 2003
CVE Candidate: CAN-2003-0779
   Reference: www.atstake.com/research/advisories/2003/a091103-1.txt


Overview:

Asterisk (http://www.asterisk.org/) is a complete PBX (Private
Branch eXchange) in software. It runs on Linux and provides all of the
features you would expect from a PBX and more. Asterisk does voice over IP
with three protocols (SIP, IAX v1 and v2, and H323), and can interoperate
with almost all standards-based telephony equipment using relatively
inexpensive hardware.

Call Detail Records (CDRs) are generated by telephony systems in order
to perform a number of functions such as billing and rating. CDRs contain
a number of fields that identify useful information about the call
including source, destination, and other items such as CallerID. These
can be generated numerous times during the call to indicate the state of
the call as well.

@stake found an issue while conducting a source code review of the CDR
logging functionality. It is possible to perform SQL injection if  an
attacker can supply a malformed CallerID string.

The interesting thing to note about this vulnerability is that is can
not only be launched via VoIP protocols, but also through fixed-line
connections (i.e. POTS - Plain Old Telephone System).


Details:

@stake discovered that minimal input validation occurred between CDR
generation and the acceptance of this data as part of the SQL query.

SQL injection is covered in great details in:

      i) SQL Injection
      http://www.spidynamics.com/papers/SQLInjectionWhitePaper.pdf   

      ii) Advanced SQL Injection
      http://www.ngssoftware.com/papers/advanced_sql_injection.pdf

As a result, it is possible for a remote unauthenticated user to
perform arbitrary database operations.


Recommendation:

@stake notified the author of this particular code on the 17th of
August. The author developed and deployed a patch silently to the CVS
on the 9th of September.

@stake recommends that if you have not deployed a CVS version
since the 9th of September 2003 to immediately do so.


Common Vulnerabilities and Exposures (CVE) Information:

The Common Vulnerabilities and Exposures (CVE) project has assigned
the following names to these issues.  These are candidates for
inclusion in the CVE list (http://cve.mitre.org), which standardizes
names for security problems.

 CAN-2003-0779  Asterisk CallerID CDR SQL injection


@stake Vulnerability Reporting Policy:
http://www.atstake.com/research/policy/

@stake Advisory Archive:
http://www.atstake.com/research/advisories/

PGP Key:
http://www.atstake.com/research/pgp_key.asc

@stake is currently seeking application security experts to fill
several consulting positions.  Applicants should have strong
application development skills and be able to perform application
security design reviews, code reviews, and application penetration
testing.  Please send resumes to jobs () atstake com.

Copyright 2003 @stake, Inc. All rights reserved.

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