Advanced Network Forensics

User/Password Crack

Hydra

Protocols supported:

cisco
cvs
ftp
ftps
icq
imap[s]
irc
Idap2[s]
mssql
mysql
nntp
oracle-listener
oracle-sid
pcanywhere
pcnfs
pop3[s]
rdp
rexec
rlogin
rsh
sip
smb
smtp[s]
smtp-enum
snmp
socks5
svn
telnet[s]
vmauthd
vnc
xmpp

Click here to download the Wireshark capture for Hydra FTP used in the above 2 images.

Click here to download the Wireshark capture for Hydra Telnet used above.

Use network anomaly detection tools

Monitor traffic flow for network anomalies
Need to know what constitutes normal activity.
- For example, connections between machines that do not normally connect, either internally or between an inside machine and an unknown outside system are inherently suspicious.
- Products: IBM's QRadar, Juniper Sky Advanced Threat Protection, Snort IPS, Cisco's Encrypted Traffic Analytics, etc.

Use SSL/TLS proxy servers

Manage 2 connections for every conversation
- Accept the encrypted connection on one network interface, decrypts the traffic, performs some operation, then re-encrypt and send the traffic to the destination
- Security operations, such as malware scanning and blocking prohibited sites.
- Take lot of processing power

NMAP Port Scanning

HOST DISCOVERY:
    -s L: List Scan - simply list targets to scan
    -s n: Ping Scan - disable port scan
    -P n: Treat all hosts as online - - skip host discovery
    -P S/P A/P U/P Y[portlist]: TCP SYN/ACK, UDP or SCTP discovery to given
ports
    -P E/P P/P M: ICMP echo, timestamp, and netmask request discovery probes
    -P O[protocol list]: IP Protocol Ping
    -n/-R: Never do DNS resolution/Always resolve [default: sometimes]
SCAN TECHNIQUES:
    -s S/s T/s A/s W/s M: TCP SYN/Connect()/ACK/Window/Maimon scans
    -s U: UDP Scan
    -s N/s F/s X: TCP Null, FIN, and Xmas scans
OS DETECTION:
    -O: Enable OS detection

C:\Documents and Settings\Administrator> nmap -sS 192.168.4 7.134
Host is up (0.00088s latency) .
Not shown: 973 closed ports
PORT STATE SERVICE
7/tcp open echo
9/tcp open discard
1 3/tcp open daytime
1 7/tcp open qotd
1 9/tcp open chargen
2 1/tcp open ftp
2 2/tcp open ssh
2 3/tcp open telnet
. .
5900/tcp open vnc
8099/tcp open unknown
MAC Address: 0 0:0C:2 9:0F:7 1:A3 (VMware)

Nmap done: 1 IP address (1 host up) scanned in 8.80 seconds

An Open port will respond with a SYN/ACK packet whilst a RST packet will indicate the port is closed.

Click here to download the Wireshark capture for NMAP used above.

UDP Scan

Null [...]

The Null Scan will send a TCP segment with no flags in the packet header. So this type of generated packets are illegal based on RFC 793.

So in Null Scan if a port is open then we will not get any response. In Null Scan no flags are set then target will not know how to handle the request. so target will discard the packet and no reply will be sent. If the port is closed, the target will send an RST packet in response.

Xmas Tree [FIN,PSH,URG]

It Sets the FIN, PSH, and URG flags, lighting the packet up like a Christmas tree.

Advantage of this scan is that it can sneak through non-stateful firewalls and packet filtering routers. Such firewalls try to prevent incoming TCP connections by blocking any TCP packets with the SYN bit set and ACK cleared. Linux iptables firewall command offers a special --syn option to implement it. Xmas scans clear the SYN bit and thus fly right through those rules.
This scan does work against most Unix-based systems.

As we can see in above picture when we send packet with FIN/PSH/URG flag to set and send it to destination if we don't get any response from Destination we will know that Port is OPEN. if we get RST in return then we know that Port is Closed.

ICMP/ARP Scan

ICMP Scan / Ping Sweep

Click here to download the Wireshark capture for the Ping Sweep used above.

ARP Scan

Click here to download the Wireshark capture for the ARP Scan used above.

Signature Detection with Snort

Detecting File Types in Payloads

There are a number of filters which can be used such as:

PNG: http contains "\x89\x50\x4E\x47"
PDF: http contains “%PDF”
GIF: http contains "GIF89a"

Refer to the article on Wireshark Filters for more details.

These filters can be used to make up Snort rules which may include Perl Compatible Regular Expressions (PCRE) such as:

# Some additional pre-processor things 
preprocessor stream5_global: track_tcp yes, \
    track_udp yes, \
    track_icmp no, \ 
    max_tcp 262144, \
    max_udp 131072, \
    max_active_responses 2, \
    min_response_seconds 5
preprocessor stream5_tcp: policy windows, detect_anomalies, require_3whs 180, \
    overlap_limit 10, small_segments 3 bytes 150, timeout 180, \
    ports client 21 22 23 25 42 53 70 79 109 110 111 113 119 135 136 137 139 143 \
        161 445 513 514 587 593 691 1433 1521 1741 2100 3306 6070 6665 6666 6667 6668 6669 \
        7000 8181 32770 32771 32772 32773 32774 32775 32776 32777 32778 32779, \
    ports both 80 81 82 83 84 85 86 87 88 89 90 110 311 383 443 465 563 591 593 631 636 901 989 992 993 994 995 1220 1414 1830 2301 2381 2809 3037 3057 3128 3443 3702 4343 4848 5250 6080 6988 7907 7000 7001 7144 7145 7510 7802 7777 7779 \
        7801 7900 7901 7902 7903 7904 7905 7906 7908 7909 7910 7911 7912 7913 7914 7915 7916 \
        7917 7918 7919 7920 8000 8008 8014 8028 8080 8085 8088 8090 8118 8123 8180 8222 8243 8280 8300 8500 8800 8888 8899 9000 9060 9080 9090 9091 9443 9999 10000 11371 34443 34444 41080 50000 50002 55555
preprocessor stream5_udp: timeout 180

# ARP Spoofing
preprocessor arpspoof
preprocessor arpspoof_detect_host: 192.168.47.200 00:0C:29:0F:71:A3

# Signature Detection
alert tcp any any -> any any (content:"GIF89a"; msg:"GIF";sid:10000)
alert tcp any any -> any any (content:"%PDF"; msg:"PDF";sid:10001)
alert tcp any any -> any any (content:"|89 50 4E 47|"; msg:"PNG";sid:10002)
alert tcp any any -> any any (content:"|50 4B 03 04|"; msg:"ZIP";sid:10003)

# Signature Detection
preprocessor sfportscan:\
        proto { all } \
        scan_type { all } \
        sense_level { high } \	
        logfile { portscan.log }

# Converted Format Detection
alert tcp any any -> any 25 (content:"/9j/4AAQSkZJRgABAQEA"; msg:"Ehealth graphic";sid:10005)
alert tcp any any -> any 25 (content:"image/gif"; msg:"GIF in email";sid:10006)

# DoS Flood Detection
alert tcp any any -> any 80 (msg:"DOS flood denial of service attempt";flow:to_server; \
detection_filter:track by_dst,  count 60, seconds 60; \
sid:25101; rev:1;)

# Bad FTP Login Detection
alert tcp any 21 -> any any (msg:"FTP Bad login"; content:"530 User "; nocase; flow:from_server,established; sid:491; rev:5;)

# Detecting email addresses in an email
alert tcp any any <> any 25 (pcre:"/[a-zA-Z0-9._%+-]+@[a-zA-Z0-9._%+-]/"; \
msg:"Email in message";sid:9000000;rev:1;)

# Detecting credit card details
alert tcp any any <> any any (pcre:"/5\d{3}(\s|-)?\d{4}(\s|-)?\d{4}(\s|-)?\d{4}/"; \
    msg:"MasterCard number detected in clear text";content:"number";nocase;sid:9000003;rev:1;)

alert tcp any any <> any any (pcre:"/3\d{3}(\s|-)?\d{6}(\s|-)?\d{5}/"; \
    msg:"American Express number detected in clear text";content:"number";nocase;sid:9000004;rev:1;)

alert tcp any any <> any any (pcre:"/4\d{3}(\s|-)?\d{4}(\s|-)?\d{4}(\s|-)?\d{4}/"; \
    msg:"Visa number detected in clear text";content:"number";nocase;sid:9000005;rev:1;)

ARP Spoofing

Enable ARP spoof detection in Snort

DDoS Detection