=============================================================================== Security Advisory CERT-NL =============================================================================== Author/Source : CERT-NL (Teun Nijssen) Index : S-93-19 Distribution : World Page : 1 Classification: External Version: Final Subject : SCO Home Directory Vulnerability Date : 17-Sep-93 ============================================================================== CERT-NL has received information concerning a vulnerability in several Santa Cruz Operation's Unix versions. The following text is taken verbatim from the advisory of CERT-CC, one of CERT-NL's sister organisations in the USA. ============================================================================= CA-93:13 CERT Advisory September 17, 1993 SCO Home Directory Vulnerability ----------------------------------------------------------------------------- The CERT Coordination Center has received information indicating that SCO Operating Systems may be vulnerable to a potential compromise of system security. This vulnerability allows unauthorized access to the "dos" and "asg" accounts, and, as a result of this access, unauthorized access to the "root" account may also occur. The following releases of SCO products are affected by this vulnerability: SCO UNIX System V/386 Release 3.2 Operating System SCO UNIX System V/386 Release 3.2 Operating System Version 2.0 SCO UNIX System V/386 Release 3.2 Operating System version 4.x SCO UNIX System V/386 Release 3.2 Operating System Version 4.0 with Maintenance Supplement Version 4.1 and/or Version 4.2 SCO Network Bundle Release 4.x SCO Open Desktop Release 1.x SCO Open Desktop Release 2.0 SCO Open Desktop Lite Release 3.0 SCO Open Desktop Release 3.0 SCO Open Server Network System Release 3.0 SCO Open Server Enterprise System Release 3.0 CERT and The Santa Cruz Operation recommend that all sites using these SCO products take action to eliminate the source of vulnerability from their systems. This problem will be corrected in upcoming releases of SCO operating systems. ----------------------------------------------------------------------------- I. Description The home directories of the users "dos" and "asg" are /tmp and /usr/tmp respectively. These directories are designed to have global write permission. II. Impact This vulnerability may allow unauthorized users to gain access to these accounts. This vulnerability may also corrupt certain binaries in the system and thus prevent regular users from running them, as well as introduce a potential for unauthorized root access. III. Solution All affected sites should follow these instructions: 1. Log onto the system as "root" 2. Choose the following sequence of menu selections from the System Administration Shell, which is invoked by typing "sysadmsh" a. Accounts-->User-->Examine--> [select the "dos" account] -->Identity -->Home directory-->Create-->Path--> [change it to /usr/dos instead of /tmp]--> confirm b. Accounts-->User-->Examine--> [select the "asg" account] -->Identity -->Home directory-->Create-->Path--> [change it to /usr/asg instead of /usr/tmp]--> confirm 3. If DOS binaries have been modified, or sites are unable to determine if modification has occurred, we strongly recommend removing and reinstalling the DOS package of the Operating System Extended Utilities. This can be done using custom(ADM). Sites may also want to check their systems for signs of further compromise. This can be facilitated through the use of programs such as COPS. Other security advice and suggestions can be found in CERT's security checklist. This checklist may be obtained through anonymous FTP from cert.org in pub/tech_tips/security_info. Note: COPS may be obtained from many sites, including via anonymous FTP from cert.org in the pub/tools directory. If you have further questions about this issue, please contact SCO Support and ask for more information concerning this CERT advisory, CA-93:13, "SCO Home Directory Vulnerability." Electronic mail: support@sco.COM Europe, Middle East, Africa: 9am-5:30pm British Standard Time (BST) ---------------------------- +44 (0)923 816344 (voice) +44 (0)923 817781 (fax) --------------------------------------------------------------------------- The CERT Coordination Center wishes to thank Christopher Durham of the Santa Cruz Operation for reporting this problem and his assistance in responding to this problem. --------------------------------------------------------------------------- CERT-NL thanks CERT-CC for sharing this information with its FIRST partners and advises its constituency to follow the CERT-CC guidelines in this advisory. CERT-NL regrets publishing this advisory during the weekend when hackers might read this earlier than System Managers, however publishes anyway because the information has become public via other channels in the past week. ============================================================================== CERT-NL is the Computer Emergency Response Team, located in The Netherlands. CERT-NL is a Full Member of the Forum of Incident Response and Security Teams (FIRST). The constituency of CERT-NL are the SURFnet connected institutions. Past CERT-NL Security Bulletins and other CERT-NL related material can be found on the anonymous FTP server of SURFnet bv: "ftp.nic.surfnet.nl" [192.87.46.3], in the directory "surfnet/net-security/cert-nl/docs/bulletin". This information is also available using email. Send an email saying "help" to "mailserv@nic.surfnet.nl". In case of computer or network security problems please contact CERT-NL or the CERT of your own constituency. Please be aware of the fact that we are one (when DST is in effect two) hour(s) ahead of Universal Time Coordinated (i.e. UTC+0100 (UTC+0200)). Email: cert-nl@surfnet.nl Phone: +31 30 310290 Fax: +31 30 340903 Snailmail: SURFnet bv Attn. CERT-NL P.O. Box 19035 NL - 3501 DA UTRECHT The Netherlands A 7*24h phonenumber is available to SURFnet SSC's and FIRST members on request =============================================================================