ptylogin used to read passwords, lock out modems, or dial out on modems
| ptylogin-dos (1681) |  High Risk |
Description:
On Unix systems that use ptylogin, a user with access to the modem tty when dialing into a Unix system (for example, having a shell account and logging in from a modem) may have the ability to:
- Lock out the modem
- Dial out with that modem
- Impersonate the login and get passwords
Platforms Affected:
- Various vendors, Unix
Remedy:
To resolve the security problems, change the kernel and getty login program (such as mgetty).
The denial of service problem cannot be fixed; however, it can be worked around with idled(8) or the described ptylogin(1) or rlogin(1) workaround. Add the fcntl flags on a tty to be "allow reopen of this tty only by root after hangup," in addition to "immutable hangup causes no further access through open fd."
Consequences:
Denial of Service
References:
- BugTraq Mailing List, Wed, 27 Jan 1999 09:01:51 +0100, UNIX shell modem access vulnerabilities at http://archives.neohapsis.com/archives/bugtraq/1999_1/0407.html.
- IBM Internet Security Systems X-Force Database, ptylogin-dos(1681) at http://xforce.iss.net/xforce/xfdb/1681.
- CVE-1999-0359: ptylogin in Unix systems allows users to perform a denial of service by locking out modems, dial out with that modem, or obtain passwords.
Reported:
Jan 27, 1999
The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall the author/distributor (IBM Internet Security Systems X-Force) be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.
For corrections or additions please email xforce@iss.net