Software Distributor Administration Guide for HP-UX 11I
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File Permissions Do Not Restrict Root
Filesystem Security 1 General Principles • Files and folders are managed • A file handle provides an by the operating system opaque identifier for a • Applications, including shells, file/folder access files through an API • File operations • Access control entry (ACE) – Open file: returns file handle – Allow/deny a certain type of – Read/write/execute file access to a file/folder by – Close file: invalidates file user/group handle • Access control list (ACL) • Hierarchical file organization – Collection of ACEs for a – Tree (Windows) file/folder – DAG (Linux) 2 Discretionary Access Control (DAC) • Users can protect what they own – The owner may grant access to others – The owner may define the type of access (read/write/execute) given to others • DAC is the standard model used in operating systems • Mandatory Access Control (MAC) – Alternative model not covered in this lecture – Multiple levels of security for users and documents – Read down and write up principles 3 Closed vs. Open Policy Closed policy Open Policy – Also called “default secure” • Deny Tom read access to “foo” • Give Tom read access to “foo” • Deny Bob r/w access to “bar” • Give Bob r/w access to “bar • Tom: I would like to read “foo” • Tom: I would like to read “foo” – Access denied – Access allowed • Tom: I would like to read “bar” • Tom: I would like to read “bar” – Access allowed – Access denied 4 Closed Policy with Negative Authorizations and Deny Priority • Give Tom r/w access to “bar” • Deny Tom write access to “bar” • Tom: I would like to read “bar” – Access -
Interesting Things You Didn't Know You Could Do With
Interesting Things You Didn’t Know You Could Do With ZFS Allan Jude -- ScaleEngine Inc. [email protected] twitter: @allanjude Introduction Allan Jude ● 13 Years as FreeBSD Server Admin ● FreeBSD src/doc committer (focus: ZFS, bhyve, ucl, xo) ● Co-Author of “FreeBSD Mastery: ZFS” and upcoming “FreeBSD Mastery: Advanced ZFS” with M. W. Lucas ● Architect of the ScaleEngine CDN (HTTP and Video) ● Host of BSDNow.tv & TechSNAP.tv Podcasts ● Use ZFS for large collections of videos, extremely large website caches, mirrors of PC-BSD pkgs and RaspBSD ● Single Handedly Manage Over 1000TB of ZFS Storage The Power of ZFS ● Integrated Redundancy (Mirroring, RAID-Z) ● Data Integrity Checking (Checksums, Scrub) ● Pooled Storage (Hot Add Disks) ● Multi-Level Cache (ARC, L2ARC, SLOG) ● Copy-on-Write (no fsck) ● Snapshots and Clones ● Quotas and Reservations ● Transparent Compression (LZ4, GZIP1-9) ● Incremental Replication (zfs send/recv) ● Datasets with Individual Inherited Properties ● Custom Properties ● Fine Grained Delegation Applying That Power ZFS has many features, but how can I use them to solve my problems? ZFS has a very well designed command line user interface, making it very easy for a sysadmin to perform common tasks (add more storage, create new datasets, change settings and properties), accomplish things that were not possible before, as well as extract a great deal more information from the storage system. ZFS Was Meant To Be Scripted # zfs list -Hp -r -o name,refer,logicalreferenced sestore5/mysql02 22001288628 24331078144 sestore5/omicron -
Application-Defined Decentralized Access Control
Application-Defined Decentralized Access Control Yuanzhong Xu, Alan Dunn, Owen Hofmann*, Michael Lee, Syed Akbar Mehdi, Emmett Witchel ! UT-Austin, Google* Access control mechanism • Simplicity • Flexibility • Easy to understand • Expressive • Less prone to bugs • Support many use cases 2 UNIX/Linux - simplicity • Linux/UNIX • User: UID • Group: GID • Admin: root user • Simplicity • Easy to understand • Less prone to bugs 3 UNIX/Linux - more flexibility • Linux/UNIX • User: UID • Need more flexibility • • Group: GID setuid binary • effective UID • Admin: root user • FS UID • Simplicity • sticky bit • Easy to understand • … • Less prone to bugs 4 setuid binaries make things tricky suEXEC of Apache server: using setuid binaries to run • Need more flexibility CGI/SSI with different UIDs • setuid binary “If you aren't familiar with • effective UID managing setuid root programs and the security • FS UID issues they present, we highly recommend that you • sticky bit not consider using • … suEXEC.” — http://httpd.apache.org/docs/2.2/suexec.html 5 Access control in server applications • A server application typically uses its own, hand- crafted program logic to enforce access control Access control is hard to get right… ! !Source of bugs: among OWASP top 10 application security risks https://www.owasp.org/index.php/Top_10_2010-Main Server application Access control Why OS access control OS CANNOT help? Inflexible OS-level access control • Numerical identifiers for Consequences principals in a flat namespace • different servers/apps CANNOT • 32-bit integer -
Intro to Unix 2018
Introduction to *nix Bill Renaud, OLCF ORNL is managed by UT-Battelle for the US Department of Energy Background • UNIX operating system was developed in 1969 by Ken Thompson and Dennis Ritchie • Many “UNIX-like” OSes developed over the years • UNIX® is now a trademark of The Open Group, which maintains the Single UNIX Specification • Linux developed by Linus Torvalds in 1991 • GNU Project started by Richard Stallman in 1983 w/aim to provide free, UNIX-compatible OS • Many of the world’s most powerful computers use Linux kernel + software from the GNU Project References: 1www.opengroup.org/unix 2https://en.wikipedia.org/wiki/Linux 2 3https://www.gnu.org/gnu/about-gnu.html This Presentation • This presentation will focus on using *nix operating systems as a non-privileged user in an HPC environment – Assumes you’re using a ‘remote’ system – No info on printing, mounting disks, etc. • We’ll focus on systems using the Linux kernel + system software from the GNU project since that’s so prevalent • Two-Part – Basics: general information, commands – Advanced: advanced commands, putting it all together, scripts, etc. 3 This Presentation • May seem a bit disjoint at first – Several basic concepts that don’t flow naturally but later topics build upon – Hopefully everything will come together, but if not… • I’ll cover (what I hope is) some useful info but can’t cover it all – People write thousand-page books on this, after all • Please ask questions! 4 Basics Terminology • User – An entity that interacts with the computer. Typically a person but could also be for an automated task. -
Linux Authentication and Access Control 4-2
Linux IDs and /etc/passwd Linux Authentication and Each user has a user id (uid) and belongs to (possibly several) groups Access Control each of which has a gid. uid and default gid are stored in /etc/passwd. E.g, in my Fedora VM: root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin Tue/Wed/Thu, September 16/17/18, 2014 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin Reading: Pollock Article; Hacking Linux Exposed sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt CS342 Computer Security mail:x:8:12:mail:/var/spool/mail:/sbin/nologin news:x:9:13:news:/etc/news: uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin Department of Computer Science ... Wellesley College lynux:x:500:500:Franklyn Turbak:/home/lynux:/bin/bash gdome:x:501:501:Georgia Dome:/home/gdome:/bin/bash cs342:x:502:502:CS342 Account:/home/cs342:/bin/bash Linux Authentication and Access Control 4-2 /etc/group /etc/shadow /etc/group defines groups and Sysadmins can define new groups, lists which users belong to them. /etc/shadow contains hashed passwords: e.g. on puma root:$1$SdMYD5fz$cr120C7tA0wDhXPrQHc3H1:15583:0:99999:7::: root:x:0:root bin:*:13665:0:99999:7::: bin:x:1:root,bin,daemon • faculty (all cs faculty) daemon:*:13665:0:99999:7::: daemon:x:2:root,bin,daemon • adm:*:13665:0:99999:7::: sys:x:3:root,bin,adm cs111sta (members of the … adm:x:4:root,adm,daemon CS111 teaching staff) lynux:$1$mUwRqvWp$2yfe5MJV0HbtdcDad8E7i/:15583:0:99999:7::: tty:x:5: • cs251stu (cs251 students) gdome:$1$d6tpFiwO$rBD5jd1ASAYatV2UuAlXW.:14274:0:99999:7::: disk:x:6:root cs342:$1$kmTSYJoG$0AnYYfykI2e/nWPRXdjwO.:14194:0:99999:7::: lp:x:7:daemon,lp mem:x:8: kmem:x:9: wheel:x:10:root Your Ubuntu VM uses longer salts and hashes: .. -
Securing Files and Verifying File Integrity in Oracle® Solaris 11.2
Securing Files and Verifying File Integrity ® in Oracle Solaris 11.2 Part No: E37122 July 2014 Copyright © 2002, 2014, Oracle and/or its affiliates. All rights reserved. This software and related documentation are provided under a license agreement containing restrictions on use and disclosure and are protected by intellectual property laws. Except as expressly permitted in your license agreement or allowed by law, you may not use, copy, reproduce, translate, broadcast, modify, license, transmit, distribute, exhibit, perform, publish, or display any part, in any form, or by any means. Reverse engineering, disassembly, or decompilation of this software, unless required by law for interoperability, is prohibited. The information contained herein is subject to change without notice and is not warranted to be error-free. If you find any errors, please report them to us in writing. If this is software or related documentation that is delivered to the U.S. Government or anyone licensing it on behalf of the U.S. Government, the following notice is applicable: U.S. GOVERNMENT END USERS. Oracle programs, including any operating system, integrated software, any programs installed on the hardware, and/or documentation, delivered to U.S. Government end users are "commercial computer software" pursuant to the applicable Federal Acquisition Regulation and agency-specific supplemental regulations. As such, use, duplication, disclosure, modification, and adaptation of the programs, including any operating system, integrated software, any programs installed on the hardware, and/or documentation, shall be subject to license terms and license restrictions applicable to the programs. No other rights are granted to the U.S. Government. -
Improving the Security of Your Unix System
A111D3 MS2DS2 NISTIR 4453 PUBLICATIONSi SRI INTERNATIONAL IMPROVING THE SECURITY OF YOUR UNIX SYSTEM Edward Roback NIST Coordinator U.S. DEPARTMENT OF COMMERCE National Institute of Standards and Technolog Gaithersburg, MD 20899 U.S. DEPARTMENT OF COMMERCE Robert A. Mosbacher, Secretary NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY John W. Lyons, Director ' QC 100 NIST .056 //4453 1990 C.2 NATIONAL INSTITUTE OF STANDARDS & TECHNOLOGY Research Informatkm Center Gaithersburg, 206S9 NISTIR 4453 SRI INTERNATIONAL IMPROVING THE SECURITY OF YOUR UNIX SYSTEM Edward Roback NIST Coordinator U.S. DEPARTMENT OF COMMERCE National Institute of Standards and Technology Gaithersburg, MD 20899 November 1990 U.S. DEPARTMENT OF COMMERCE Robert A. Mosbacher, Secretary NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY John W. Lyons, Director . , ’ ^s'M^ , ' v.y.i;>;n • ^ M V '#.7 r-.- ,?• r ;'53.£ J' }.. id Aa ai'” .c-y 'i .’ll' - - ' j .r : t *W ly'-; .i'll , ' i ’ *' 1 &S>f - , ' i:/>R -'j i 'I :^‘.::*B: ;.^. > ' ir-': Hi' ' ''•issTSi. fli, •' :i)n' - r^'-C '.I'riJ %P -qj Hr^V‘5 V f }' '^'^<1 A' V •- r, r, \\ ^ Oi , Y-; ’U ' . fQ'i - (J'; • . ' s- i' ;^ O' LjfJOO i % ! ' i; i ‘ ' ^ y' £•, - t V' OJ ,C ,;»: .-.tr •• ^ L'-.„;:i \'i .jii' t; ' '‘-' .. ; -'j .' v x;: 1 :r . m: 4 1 (jqi/. '1 * ibi,i '' .,•>- . ..-/ . ^ .. .t. "' » i y''"o j -0 -' ' , V.' ' •i .V/ .i-’ ’^V. ’‘M Final Report • April 1990 IMPROVING THE SECURITY OF YOUR UNIX SYSTEM David A. Curry, Systems Programmer Information and Telecommunications Sciences and Technology Division ITSTD-721-FR-90-21 333 Ravens\wood Avenue • Menlo Park. -
Model Checking an Entire Linux Distribution for Security Violations
Model Checking An Entire Linux Distribution for Security Violations by Benjamin W. Schwarz Research Project Submitted to the Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, in partial satisfaction of the requirements for the degree of Master of Science, Plan II. Approval for the Report and Comprehensive Examination: Committee: David Wagner Research Advisor (Date) * * * * * * * Doug Tygar Second Reader (Date) Abstract Software model checking has become a popular tool for verifying pro- grams’ behavior. Recent results suggest that it is viable for finding and erad- icating security bugs quickly. However, even state-of-the-art model checkers are limited in use when they report an overwhelming number of false positives, or when their lengthy running time dwarfs other software development pro- cesses. In this paper we report our experiences with software model checking for security properties on an extremely large scale—an entire Linux distribu- tion consisting of 839 packages and 60 million lines of code. To date, we have discovered 108 exploitable bugs. Our results indicate that model checking can be both a feasible and integral part of the software development process. 2 Contents 1 Introduction 5 2 The MOPS Model Checker 6 2.1 Specification of Security Properties . 7 2.2 Scalability . 8 2.3 Error Reporting . 8 2.4 Efficient Model Checking with Pattern Variables . 9 2.4.1 Current implementation . 9 2.4.2 More Efficient Algorithms . 10 2.5 User Interface for Error Reporting . 11 2.6 Resource Usage . 12 3 Checking Security Properties 12 3.1 TOCTTOU . 13 3.2 A Standard File Descriptor Attack . -
Redundancy and Access Permissions in Decentralized File Systems
Lehrstuhl für Netzarchitekturen und Netzdienste Fakultät für Informatik Technische Universität München Redundancy and Access Permissions in Decentralized File Systems Johanna Amann Vollständiger Abdruck der von der Fakultät für Informatik der Technischen Universität München zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) genehmigten Dissertation. Vorsitzender: Univ.-Prof. Dr. Johann Schlichter Prüfer der Dissertation: 1. Univ.-Prof. Dr. Georg Carle 2. Univ.-Prof. Dr. Kurt Tutschku, Universität Wien 3. TUM Junior Fellow Dr. Thomas Fuhrmann Die Dissertation wurde am 20.06.2011 bei der Technischen Universität München eingereicht und durch die Fakultät für Informatik am 05.09.2011 angenommen. Zusammenfassung Verteilte Dateisysteme sind ein Thema mit dem sich die Informatik immer wieder aufs Neue auseinandersetzt. Die ersten verteilten Dateisysteme sind schon sehr kurz nach dem Aufkommen von Computernetzen entstanden. Traditionell sind solche Systeme serverbasiert, d. h. es gibt eine strikte Unterscheidung zwischen den Systemen welche die Daten speichern und den Systemen welche die Daten abrufen. Diese Architektur hat Vorteile; es wird zum Beispiel angenommen, dass die Server vertrauenswürdig sind. Außerdem gibt es eine inhärente lineare Ordnung der Dateioperationen. Auf der anderen Seite sind solche zentralisierten Systeme schlecht skalierbar, haben einen hohen Administrationsaufwand, eine geringe Fehlertoleranz oder sind teuer im Betrieb. Im Verlauf des letzten Jahrzehnts wurde eine neue Art von -
Implementation of Process Swapping in MINIX (A Message Passing Oriented Operating System)
An Implementation of Process Swapping in MINK (A Message Passing Oriented Operating System) , by Stanley George Kobylanski B.S., Pennsylvania State University, 1972 A MASTER'S REPORT submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Computing and Information Sciences KANSAS STATE UNIVERSITY Manhattan, Kansas 1989 Approved by: c/tftxbr^/l- <^Wl4u>ti) Major Professor k*,3 CZ A112D& 317bftu CONTENTS 1. INTRODUCTION 1 1.1 Purpose of Operating Systems 1 1.2 MTNIX Operating System 2 1.2.1 Introduction 2 12.2 MTNIX and UNIX 3 1.2.2.1 General Description 3 1.2.2.2 UNIX Description 4 1.2.2.3 MTNIX Description 6 1.2.3 MTNIX Limitations 9 1.2.3.1 MTNIX Problem 10 2. REQUIREMENTS 12 2.1 Extend Memory 12 2.2 Maintain Existing Functions 12 2.3 Maintain MTNIX Structure 12 2.4 User Administration 13 2.5 Performance 13 3. DETAILED DESIGN 14 3.1 Introduction 14 3.2 Process Swapping 14 3.2.1 Purpose of Swapping 14 3.2.2 Swapping Functions 15 3.2.3 Alternatives to Swapping 15 3.2.3.1 Increased Memory 15 3.2.3.2 Demand Paging 15 3.3 General Design 16 3.3.1 Introduction 16 3.3.2 Overview 18 3.3.3 Swapping Functions 20 3.3.3.1 Swap Device 20 3.3.3.2 Swapping Out Processes 20 3.3.3.3 Swapping In Processes 26 3.4 Detailed Module Description 27 3.4.1 Introduction 28 3.4.2 Kernel - Management and Decisions 28 3.4.2.1 Swap Task 28 - i 3.4.2.1.1 Swap Task Stales 30 3.4.2.1.2 Swap Task Transitions 30 3.4.2.1.3 Swap Out Algorithm 33 3.4.2.1.4 Swap In Algorithm 35 3.4.2.2 Clock Task 35 3.4.2.3 System Task 36 3.4.3 Memory -
Operating Systems Security
Operating Systems Security 1 The Boot Sequence • The action of loading an operating system into memory from a powered-off state is known as booting or bootstrapping. • When a computer is turned on, it first executes code stored in a firmware component known as the BIOS (basic input/output system). • On modern systems, the BIOS loads into memory the second-stage boot loader, which handles loading the rest of the operating system into memory and then passes control of execution to the operating system. 2 BIOS Passwords • A malicious user could potentially seize execution of a computer at several points in the boot process. • To prevent an attacker from initiating the first stages of booting, many computers feature a BIOS password that does not allow a second- stage boot loader to be executed without proper authentication. 3 Hibernation • Modern machines have the aBility to go into a powered-off state known as hibernation. • While going into hiBernation, the OS stores the contents of machine’s memory into a hibernation file (such as hiBerfil.sys) on disk so the computer can Be quickly restored later. • But… without additional security precautions, hiBernation exposes a machine to potentially invasive forensic investigation. 1. User closes a laptop computer, putting it into hibernation. 2. Attacker copies the hiberfil.sys file to discover any unencrypted passwords that were stored in memory when the computer 4 was put into hibernation. Event Logging • Keeping track of what processes are running, what other machines have interacted with the system via the Internet, and if the operating system has experienced any unexpected or suspicious behavior can often leave important clues not only for troubleshooting ordinary problems, but also for determining the cause of a security breach. -
How to Open a File and Not Get Hacked
How to Open a File and Not Get Hacked JamesA.Kupsch BartonP.Miller Computer Sciences Department University of Wisconsin Madison, WI 53706-1685 USA {kupsch,bart}@cs.wisc.edu Abstract the creation or modification of files in unexpected locations as in IBM’s DB2 [4] and Xsession [3], and (4) weak file Careless attention to opening files, often caused by prob- permissions resulting from incorrect use of the API. lems with path traversal or shared directories, can expose These types of problems are especially problematic applications to attacks on the file names that they use. In when the target application is running with elevated priv- this paper we present criteria to determine if a path is safe ileges such as root, and the file used in the attack is in a from attack and how previous algorithms are not sufficient directory that is writable by the adversary. If the target ap- to protect against such attacks. We then describe an algo- plication is running with elevated privilege, it can modify rithm to safely open a file when in the presence of an attack files or disclose file contents that the adversary would not (and how to detect the presence of such an attack), and pro- normally be able to access and compromise the entire sys- vide a new library of file open routines that embodies our tem. If the target application is running as an ordinary user, algorithm. These routines can be used as one-for-one sub- attacks are still possible on data owned by the user running stitutes for conventional POSIX open and fopen calls.