Description
The design of the dialplan functionality in Asterisk Open Source 1.2.x, 1.4.x, and 1.6.x; and Asterisk Business Edition B.x.x and C.x.x, when using the ${EXTEN} channel variable and wildcard pattern matches, allows context-dependent attackers to inject strings into the dialplan using metacharacters that are injected when the variable is expanded, as demonstrated using the Dial application to process a crafted SIP INVITE message that adds an unintended outgoing channel leg. NOTE: it could be argued that this is not a vulnerability in Asterisk, but a class of vulnerabilities that can occur in any program that uses this feature without the associated filtering functionality that is already available.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | asterisk | 1:1.6.2.6-1 | — |
References
- http://svn.asterisk.org/svn/asterisk/branches/1.2/README-SERIOUSLY.bestpractices.txt
- 39096 third-party-advisory
- 1023637 vdb-entry
- FEDORA-2010-3724 vendor-advisory
- 20100218 AST-2010-002: Dialplan injection vulnerability mailing-list
- 38641 third-party-advisory
- http://downloads.digium.com/pub/security/AST-2010-002.html
- ADV-2010-0439 vdb-entry
- asterisk-dial-weak-security(56397) vdb-entry