PROBLEM: Vulnerabilities in several implementations of the FTP daemon. PLATFORM: Unix systems with the following implementations of the FTP daemon: DECWRL ftpd versions before 5.93, wuarchive ftpd versions 2.0-2.3, and BSDI ftpd version 1.1. prior to patch 5. DAMAGE: Anyone (remote or local) can gain root access on a host running a vulnerable daemon. SOLUTION: Upgrade to a secure version of the FTP daemon.
VULNERABILITY Details of these vulnerabilities are being actively discussed ASSESSMENT: on several Internet mailing lists. CIAC urges affected sites to upgrade immediately.
CIAC has received information concerning the existence of two vulnerabilities in FTP daemons derived from the DECWRL ftpd source code. The following FTP daemons are known to be vulnerable:
- DECWRL ftpd versions before 5.93 - wuarchive ftpd versions 2.0-2.3 - BSDI ftpd version 1.1 prior to patch 5
The first vulnerability involves the SITE EXEC command feature of these FTP daemons. It only affects those daemons in which the SITE EXEC functions have been explicitly activated; they are not enabled by default. The vulnerability allows any user, remote or local, to execute commands as root on the system running the FTP daemon. The second vulnerability is the result of a race condition in the daemon. It allows the creation of setuid root files on the FTP server, permitting unauthorized access to the system.
There is no known workaround to remove both vulnerabilities; therefore, CIAC strongly advises affected sites to upgrade to one of the versions of the daemon listed below. If an upgrade cannot be completed in a timely manner, FTP service should be disabled by commenting out the ftp configuration line in /etc/inetd.conf and restarting inetd. Disabling only anonymous FTP does not remove the vulnerabilities.
Upgrade Information
Version 2.4 of wuarchive ftpd is available via anonymous FTP from wuarchive.wustl.edu in the directory /packages/wuarchive-ftpd. A patch to upgrade from version 2.3 to 2.4 is also available:
BSD SVR4 File Checksum Checksum MD5 Digital Signature ----------------- --------- --------- -------------------------------- wu-ftpd-2.4.tar.Z 38213 181 20337 362 cdcb237b71082fa23706429134d8c32e patch_2.3-2.4.Z 09291 8 51092 16 5558a04d9da7cdb1113b158aff89be8f
Version 5.93 of DECWRL ftpd is available via anonymous FTP from gatekeeper.dec.com in the directory /pub/misc/vixie:
BSD SVR4 File Checksum Checksum MD5 Digital Signature ----------------- --------- --------- -------------------------------- ftpd.tar.gz 38443 60 1710 119 ae624eb607b4ee90e318b857e6573500
For BSDI systems, patch 005 should be applied to version 1.1 of the BSD/386 software. The patch file is available via anonymous FTP from ftp.bsdi.com in the directory /bsdi/patches-1.1:
BSD SVR4 File Checksum Checksum MD5 Digital Signature ----------------- --------- --------- -------------------------------- BU110-005 35337 272 54935 543 1f454d4d9d3e1397d1eff0432bd383cf
For additional information or assistance, please contact CIAC:
Voice: 510-422-8193 FAX: 510-423-8002 STU-III: 510-423-2604 E-mail: ciac@llnl.gov