Vulnerability Note VU#464817

Sun Solaris asppls(1M) vulnerable to arbitrary file overwriting via symlink redirection of temporary file

Overview

Sun Solaris asppls(1M) creates temporary files insecurely, leading to possible local root compromise.

I. Description

Sun Microsystems describes the function of asppls(1M) as follows:

aspppd is the link manager for the asynchronous data link protocol specified in RFC1331, The Point-to-Point Protocol (PPP) for the Transmission of Multi-protocol Datagrams over Point-to-Point Links. It is a user level daemon that works in concert with the IP-Dialup driver (ipdcm) and PPP streams module ( ppp(7M)) to provide IP network services over an analog modem using dialed voice grade telephone lines. The link manager automates the process of connecting to a peer (remote) host when PPP service with that host is required. The connection process can be initiated either by sending an IP datagram to a (disconnected) peer host or by receiving a notification that a peer host desires to establish a connection. aspppls is the login service that connects the peer host machine to aspppd. aspppls is invoked by the serial port monitor when a peer machine logs into a PPP-enabled account. Its purpose is to cause the link manager to accept the incoming call.

A flaw in asppls(1M) allows a local attacker to overwrite or create any file on a Solaris 8 host.

II. Impact

A local attacker may be able to elevate his or her privileges.

III. Solution

Apply a patch.

Workaround

The following workaround is taken from Sun Alert ID: 46903

If asynchronous PPP is not being used at the customer site, the setuid permissions on the aspppls(1M) binary could be removed via the following command run as root:

# chmod u-s /usr/sbin/aspppls

The asynchronous PPP packages could also be removed if asynchronous PPP is not being used via the following command run as root:

# pkgrm SUNWapppr SUNWpppdu

Systems Affected

Vendor	Status	Date Notified	Date Updated
Sun Microsystems Inc.	Vulnerable	27-Sep-2002

References

http://sunsolve.Sun.COM/pub-cgi/retrieve.pl?doc=fsalert%2F46903

Credit

Thanks to Sun Microsystems for creating the security bulletin upon which this document is based. Kevin Kotas, of eSecurityOnline is credited with discovering this vulnerability.

This document was written by Ian A Finlay.

Other Information

Date Public:	2002-09-09
Date First Published:	2002-09-27
Date Last Updated:	2003-04-15
CERT Advisory:
CVE-ID(s):
NVD-ID(s):
US-CERT Technical Alerts:
Metric:	2.14
Document Revision:	11

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