awareness of security exploits and their causes

Awareness of Security Exploits and Their Causes

Prabhaker MatetiWright State University

Aug – Dec 2014 On Sabbatical at Amrita Viswa Vidyapeetham

Security Awareness 2014

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Prabhaker Mateti

Some Numbers

Security Awareness 2014 3

Amazon.com book search

2003 2014Network security 813 31564Internet security 1009 18995Computer security 2871 39812System security 1521 107303Homeland security 80 24629Security 32000 194118

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Security Incidents / CERT

2013: 100000+ “CERT uses the word "incident" as an

administrative term … A single "incident" can involve anything

from a single host computer to a very large number of host computers, at a single site or at hundreds of thousands of sites.”

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Number of Hosts in the DNS

2003171,638,297 2000 72,398,092

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Sizes of Some Software

MLOC

1993 Windows NT 3.1 6

1996 Windows NT 4.0 11

2001 Windows XP 45

2000 Linux Debian 2.2 55

2012 Linux Debian 7.0 419

2005 Mac OS X 10.4 86

2001 Linux Kernel 2.4.2 2

2012 Linux Kernel 3.6 16

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Bu

gs p

er T

hou

san

d L

OC

Table from “Code Complete” book Not to be taken as too authentic Don’t believe the 0 at the low end

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Terms …


“So you got r00ted.’’

Your machine has been compromised. root = administrator = super-user An unauthorized user has obtained root

privileges. A rootkit may have been installed. Forensic analyses made with tools

existing on that system are unreliable.

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Denial of Service (DoS)

We think of computer systems as providing services to authorized users.

When a system is deliberately made to crash, or made to run legitimate users' programs so very slowly that it is unusable, we refer to it as a "denial of service attack."

The attacker accomplishes this by running certain cleverly composed programs, and is pre-aware of the consequences.

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Black Hats v. White Hats

Black hats are the "bad" guys in that they use their knowledge to unauthorizedly break into even more systems, and pass their knowledge to other insiders.

White hats are the "good" guys: they are mostly into forensics and prevention of attacks.

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Vulnerability, …

Vulnerability: A weakness that can be exploited to cause damage.

Attack: A method of exploiting a vulnerability.

Threat: A motivated, capable adversary that mounts attacks.

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Hacker v. Attacker v. Intruder

Hacker = One who programs enthusiastically, even obsessively.

An expert at a particular program, as in ‘a Unix hacker’.

A hacker enjoys exploring the details of programmable systems and how to stretch their capabilities.

A hacker has ethics.

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Malware

Any “program” that has a “malicious” intent …

Viruses + Worms + Trojans + …

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Viruses

Viruses are "programs" that modify other programs on a computer, inserting copies of themselves.

Viruses are not officially programs:› They cannot run on their own.› Need to have some host program.› When the host program is run, the virus runs.

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Worms

Worms are programs that propagate from computer to computer on a network.

Worms can run independently. Worms may have (different) portions of

themselves running on many different machines.

Worms do not change other programs, although they may carry other code that does.

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Trojans

A Trojan mimics the functionality of its namesake legitimate program.

But has a hidden “agenda.” Ex: wu-ftpd Trojan - Login with specific

user/password gives a root shell.

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Backdoors

Also called trap doors. Allow unauthorized access to a system. The absence of backdoors cannot be

established.

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System Security

“System Security” = Computer Security + Network Security

Trojan Horses, Viruses and Worms Privacy and Authentication TCP/IP exploits Firewalls Secure Configuration of Personal Machines Buffer Overflow and Other Bug Exploitation Writing Bug-free and Secure Software Secure e-Commerce Transactions …

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Current practices

and their problems


Improper Configuration

Out of the box installations are rarely properly configured.

Standard user accounts with standard passwords.

Running unneeded services. Leaving sensitive files read/write-open.

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Fortification

Start with a properly configured system.

Delete weak or unneeded components. Add protective layers. Keep detailed logs.

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Hardened OS

Often “equated” with fortification. Rebuilding an OS from the same source

code but by using a more rigorous compiler.

Redesigning portions of an OS. Statically v. dynamically configured.

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Rootkits

“A rootkit is a collection of tools and utilities that attackers use to hide their presence and gather data to help them infiltrate further across the network. Rootkits insert backdoors, install Trojans, and patch existing programs.”

Installed after the attacker gains access. Cannot be detected by firewalls or anti-virus

scanners. 200+ results for search “rootkit’’ on

www.packetstormsecurity.org Prabhaker Mateti

http://www.packetstormsecurity.org/


Windows Rootkit Examples

null.sys HE4Hook Hacker Defender Slanret He4Hook Vanquish Fu …

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Linux Rootkit Examples

Linux Rootkit (LRK) TeLeKit Adore Knark t0rnkit Kernel Intrusion System (KIS) …

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Booting Up

BIOS OS Kernel Initialization User logins

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boot.ini

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[boot loader]timeout=30default=multi(0)disk(0)rdisk(0)partition(9)\WINDOWS[operating systems]C:\bootsect\hdc3grub.bin="Booting From FAT32on120GB" multi(0)disk(0)rdisk(0)partition(3)\WINDOWS="Windows XP Pro r0 p3" /fastdetectmulti(0)disk(0)rdisk(0)partition(9)\WINDOWS="Windows XP Pro r0 p9" /fastdetectmulti(0)disk(0)rdisk(0)partition(14)\WINDOWS="Windows XP Pro r0 p14" /fastdetectC:\bootsect\hdc3grub.bin="Linux via Grub"


/boot/grub/menu.lst

timeout 10default 1

title failsafekernel (hd0,6)/boot/vmlinuz root=/dev/hda7 failsafe devfs=nomount

hdc=ide-scsi acpi=offinitrd (hd0,6)/boot/initrd.img

title linux-smpkernel (hd0,6)/boot/vmlinuz-smp root=/dev/hda7 devfs=mount

hdc=ide-scsi acpi=offinitrd (hd0,6)/boot/initrd-smp.img

title windowsroot (hd0,0)chainloader +1

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Human User Authentication

Something you know (e.g., a password or other secret);

Something you have (e.g., smart card, credit card);

Something you are (e.g., fingerprints, retinal scan, voice print).

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Passwords

Weak passwords; social engineering. telnet, ftp, … passwords travel the

network in the clear; can be sniffed. One Time Passwords

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Cryptography

"Computationally Infeasible” N = 2^a * 3^b * 5^c * 7^d * ...

One way hash function› takes a variable-length input sequence of

bytes and converts it into a fixed-length sequence.

› designed to be computationally infeasible to reverse the process

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Symmetric Keys

sender and receiver of a message share a single, common key.

If ct = encryption (pt, key), then pt = decryption (ct, key).

DES IDEA Blowfish

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Public and Private Keys

a public key known to everyone, and a private or secret key known only to the recipient of the message

The two keys are mathematically related, yet it is computationally infeasible to deduce one from the other.

A global registry of public keys is needed RSA

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Man-in-the-Middle Attack

The public key-based communication between say Alice and Bob is vulnerable.

Let us assume that Mallory, a cracker, not only can listen to the traffic between Alice and Bob, but also can modify, delete, and substitute Alice's and Bob's messages, as well as introduce new ones. Mallory can impersonate Alice when talking to Bob and impersonate Bob when talking to Alice. Here is how the attack works.

Bob sends Alice his public key. Mallory intercepts the key and sends her own public key to Alice.

Alice generates a random session key, encrypts it with "Bob’s" public key (which is really Mallory's), and sends it to Bob.

Mallory intercepts the message. He decrypts the session key with his private key, encrypts it with Bob's public key, and sends it to Bob.

Bob receives the message thinking it came from Alice. He decrypts it with his private key and obtains the session key.

Alice and Bob start exchanging messages using the session key. Mallory, who also has that key, can now decipher the entire conversation.

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Buffer Overflow

“Quick: What's the computer vulnerability of the decade? It's not the Y2K bug, according to computer science and security analysts, but a security weakness known as the buffer overflow .”

Executable code is injected on to the runtime stack.

The return address that was on the stack is modified to point to the beginning of this code.

The executable code chosen produces a shell. A root-privileged program is so exploited; so, you

are r00ted.

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Buffer Overflow

Many of the Top 20 vulnerabilities are buffer overflow problems.

Caused by a simple class of programming errors.

C and its promiscuous style.

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Network Security

Ethernet is a broadcast medium.So is: wifiPacket switching.


Security of the Connection

Least secure: Wireless networking Second least secure: Always-on wired

connections Second most secure: Intermittent wired

connections (dial-up) Most secure: Never connected.

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TCP/IP Design Problems

Designed with too little concern for security.

All data, including various fields in the protocol headers, are sent in the clear.

Sender and Receiver in the packet can be spoofed.

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IP4 Spoofing

IP address: a.b.c.d, 4-bytes. IP packet contains the IP addresses of

sender and receiver. Everything in the clear. IP spoofing replaces the IP address of

(usually) the sender or (in rare cases) the destination with a different address.

Services that authenticate based on the IP addresses are vulnerable.

RPC, NFS, r-commands (rlogin, rsh, rcp, etc.), X windows, …

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IP Fragment Attacks

When packets are too large to be sent in a single IP packet, due to interface hardware limitations for example, they can be split up by an intermediate router.

The final destination will reassemble all the fragments of an IP packet.

Attackers create artificially fragmented packets in order to circumvent firewalls that do not perform packet reassembly.

In the IP layer implementations of nearly all OS, there are bugs in the reassembly code.

Attackers create fragments that trigger these bugs.

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TCP Exploits

The SYN Flood Connection Killing by RST Closing a Connection by FIN Connection Hijacking

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Covert Channels

Sending of “data” not in the payload, but via other “places.”

Headers. Sequence numbers.

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Probing

Port Scanning is one of the most popular among the reconnaissance techniques.

Find open ports Fingerprint the OS

Stealth scan, Bounce scan, … nmap

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Sniffers

A packet sniffer is a program that eavesdrops on the network traffic.

It copies packets as they pass the NIC. An NIC in the normal mode reads packets

destined to its specific MAC address, and all other packets are ignored.

An NIC in promiscuous mode, receives all packets regardless of the MAC address.

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Distributed Denial of Service (DDoS)

Several machines participate in a DoS attack of a victim.

These participants are often compromised innocent machines serving the “attacks.”

A remote client triggers the attack servers.

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DNS Attacks

Domain Name Service protocol is inherently vulnerable.

DNS cache poisoning. BIND 8 is the most popular DNS server. DNS servers running BIND are not up to

date with security patches and software updates.

On October 21, 2002, 9 of the 13 root name servers were the target of a DDoS attack.

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Mobile Computing


Smart Phones

Highly capable networked computer systems› Quad-core 1.2 GHz CPUs› 1 GB RAM› 16 GB persistent storage

Standard : GSM, Wi-Fi, GPS, Bluetooth, camera, microphone, various sensors

Used by millions of computer-illiterates Constrained by battery capacity

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Android Devices 2014

Android’s global market share 78.4

Number of daily activations of Android devices 1,500,000

Global shipments of Android smartphones 1,133Mn

Number of Android smartphone users in the U.S. 76Mn

Number of apps downloaded from the Play store 50Bn

Average unique monthly users of Facebook app 42.38Mn

http://www.statista.com/topics/876/android/

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http://www.statista.com/topics/876/android/


Android Security

Soon to match PCs in malware Kaspersky reports attacks per month

› Aug 2013: 69,000› Mar 2014: 650,000

Pocket Spy? Hot Research Topic

› 1000+ papers› Permissions: 500+› Privacy improvements: 50+

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Protecting Our Systems


Security Software

Secure Shell, PGP, … Firewall Kits Tools

› Top 50 Security Tools survey from www.nmap.org› http://www.packetfactory.net› nmap, SAINT, …› tcpdump, ethereal, snort, …› Password cracking› Tcpwrapper

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http://www.nmap.org/

http://www.packetfactory.net/


SSH (Secure Shell)

telnet, rlogin, … do not authenticate the remote machine; SSH does.

The password that the user types as part of the login ritual is sent as clear text by telnet and rlogin; SSH sends it encrypted.

The data being sent and received by the RTF is also sent as clear text; SSH sends and receives it in encrypted form.

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SSH (Secure Shell)

ssh1 v. ssh2 SSH exploits do exist. Susceptible to man in the middle attack Encryption and decryption consumes

computing and elapsed time. Can be a nuisance. If the remote system

has been legitimately reinstalled ...

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SSH client and servers

ssh putty ttermpro openssh

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VPN (Virtual Private Network)

Data travels over public networks, usually the Internet.

The information needed to allow the data packets to be routed between the source node and the destination node is available to the public medium as in ordinary TCP/IP traffic,

But, all other information is encrypted. PPTP, L2TP, IPsec

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File Integrity

“Is the file what I installed? Did it change?”

Time stamps, file size, … are not reliable. MD5 checksums.

The MD5 algorithm takes as input an arbitrary length byte sequence and produces a 16-byte "fingerprint" or "message digest" of the input. It is conjectured that it is computationally infeasible to produce two messages having the same message digest, or to produce any message having a given pre-specified target message digest.

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Scanning for “Viruses”

Scanners hook themselves in the read/write methods of the file sys.

Search for patterns in the file content. Search for specific file names, … Can yield false positives. Can miss identifying malware.

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Packet Filters

Drop packets based on matching certain parts: IP addresses, port numbers, protocols, flags.

Network Address Translation - NAT IP port forwarding iptables -A FORWARD -d ! 192.168.17.0/24 -i eth1 -j

prvt-extrn iptables -A FORWARD -s 130.108.17.0/24 -i eth2 -j dmz-extrn iptables -A FORWARD -d 130.108.17.0/24 -i eth0 -j extrn-dmz iptables -A FORWARD -j DROP -l

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Firewalls

Packet filters Bastion Host Proxy services Stateful Inspection Three Myths of Firewalls

Firewalls make the assumption that the only way in or out of a corporate network is through the firewalls; that there are no "back doors" to your network.

Firewalls make the assumption that all of the bad guys are on the outside of the firewall, and everyone on the inside of the can be considered trustworthy.

With macros, JavaScript, Java, … executable fragments can be embedded inside data.

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Intrusion Detection

Detect probes. Constantly check file integrity. Constantly check which ports are open

and why. Keep detailed logs of suspicious

activity on a separate system.

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Causes


Bugs in Privileged Software

Many bugs are exploitable from a security perspective. › A simple array-index out of bounds bug

can lead to computer being owned by the attacker.

2014 State of the Art: Cannot produce bug-free software (unless tiny)

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Improper Configuration

Out of the box installations are rarely properly configured.

Standard user accounts with standard passwords.

Running unneeded services. Leaving sensitive files read/write-open.

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TCP/IP Design Problems

Designed with too little concern for security.

All data, including various fields in the protocol headers, are sent in the clear.

Sender and Receiver in the packet can be spoofed.

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OS Design

Too focused on performance Not enough on security Too much trust on components

› E.g., kernel trusts /sbin/init

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Further Reading


Security Web Sites

“There is an oceanic amount of material on network security available over the Internet.”

-- A Web Page. 10000+ web sites Select list follows

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A Few Chosen Security Websites

www.incidents.org www.cert.org www.cerias.purdue.edu www.securityfocus.com lwn.net/security www.microsoft.com/security www.phrack.org

Prabhaker Mateti

http://www.incidents.org/

http://www.cert.org/

http://www.cerias.purdue.edu/

http://www.securityfocus.com/

http://www.microsoft.com/security

http://www.phrack.org/


Mateti/Security Links

CEG 4420 Cyber Security UG coursewww.cs.wright.edu/~pmateti/Courses/4420

Android Internals and Security at Amritawww.cs.wright.edu/~pmateti/Courses/7900

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http://www.cs.wright.edu/~pmateti/Courses/4420




awareness of security exploits and their causes

Documents

host program

composed programs

single host computer

legitimate users programs

computer systems

linux kernel

malwareany program

single incident