https://www.stateoftheinternet.com/resources-web-security-threat-advisories-2015-xor-ddos-attacks-linux-botnet-malware-removal-ddos-mitigation-yara-snort.html Recently the Akamai Security Intelligence Response Team (SIRT) released its analysis of the XOR DDoS threat, Trojan malware used to infect and hijack Linux-based systems. Attacks from the XOR DDoS botnet have ranged from low, single-digit Gbps attacks to 150+ Gbps. Watch this brief slideshow for the fast facts, and then get detection and mitigation recommendations from the full XOR DDoS Threat Advisory at www.stateoftheinternet.com/xorddos.

1. akamai.com
[XOR DDoS Threat Advisory]

2. • The XOR DDoS botnet has produced DDoS attacks from a
few Gbps to 150+ Gbps
• The gaming sector has been the primary target, followed by
educational institutions
• The botnet has attacked up to 20 targets per day, 90% of
which were in Asia
• XOR DDoS is an example of attackers building botnets of
Linux systems instead of Windows-based machines
• The malware spreads via Secure Shell (SSH) services
susceptible to brute-force attacks due to weak passwords
What is the XOR DDoS threat
2 / [The State of the Internet] / Security Threat Advisory

3. • Execution requires root privileges
• The malware creates two copies of itself:
• One copy in the /boot directory with a filename composed of
10 random alpha characters
• One copy in /lib/udev with the filename udev.
Binary infection indicators
3 / [The State of the Internet] / Security Threat Advisory
root@ubuntu:/boot# ls -la | egrep -i “ [a-z]{10}$”
-rwxr-x--- 1 root root 619760 Aug 12 07:56 snvnszjeez
root@ubuntu:/boot# ls -la /lib/udev/udev
-r-------- 1 root root 619760 Aug 12 07:56 /lib/udev/udev

4. • Listing the open files with lsof shows the process that use
the malware
Binary infection indicators
root@ubuntu:/boot# lsof | grep snvnszjee
snvnszjee 5671 root cwd DIR 8,1 4096 918696 /home/user/Desktop
snvnszjee 5671 root rtd DIR 8,1 4096 2 /
snvnszjee 5671 root txt REG 8,1 619760 802459 /boot/snvnszjeez
snvnszjee 5671 root 0u CHR 1,3 0t0 5626 /dev/null
snvnszjee 5671 root 1u CHR 1,3 0t0 5626 /dev/null
snvnszjee 5671 root 2u CHR 1,3 0t0 5626 /dev/null
snvnszjee 5671 root 3u sock 0,7 0t0 446764 can’t identify protocol
4 / [The State of the Internet] / Security Threat Advisory

5. • Communications between the C2 and bot occur over TCP port 3502
• The bot registers itself with the C2 using this payload
Toolkit analysis
5 / [The State of the Internet] / Security Threat Advisory
17:12:16.984371 IP x.x.x.x.49316 > y.y.y.y.3502: Flags [P.], seq 29:301, ack 1, win 29200, length 272
0x0000: 4500 0138 4a85 4000 4006 8cbf c0a8 ac9e E..8J.@.@.......
0x0010: xxxx xxxx c0a4 0dae 148c 0d91 8b7e 29a8 .............~).
0x0020: 5018 7210 bca1 0000 ab41 3246 4133 3641 P.r......A2FA36A
0x0030: bebe c6ca 071f 7703 6c72 1f75 731e 5124 ......w.lr.us.Q$
0x0040: 2f24 4b5c 5731 4630 4242 3246 4133 3641 /$KW1F0BB2FA36A
0x0050: 4141 3935 3431 4630 4242 3246 4133 3641 AA9541F0BB2FA36A
0x0060: 4141 3935 3431 4630 4242 3246 4133 3641 AA9541F0BB2FA36A
0x0070: 4141 3935 3458 7008 7442 3246 4133 3641 AA954Xp.tB2FA36A
0x0080: 4141 3935 3431 4630 4242 3246 4133 3641 AA9541F0BB2FA36A
0x0090: 4141 3935 3431 4630 4242 3246 4133 3641 AA9541F0BB2FA36A
0x00a0: 4141 3935 3431 4630 4242 3246 4133 3641 AA9541F0BB2FA36A
0x00b0: 4141 3935 3431 771a 7070 0b72 4133 3641 AA9541w.pp.rA36A
0x00c0: 4141 3935 3431 4630 4242 3246 4133 3641 AA9541F0BB2FA36A
0x00d0: 4141 3935 3431 4630 4242 3246 4133 3641 AA9541F0BB2FA36A
0x00e0: 4141 3935 3431 4630 4242 3246 4133 3641 AA9541F0BB2FA36A
0x00f0: 4141 3935 3431 4659 2028 5a3c 235f 4c30 AA9541FY.(Z<#_L0
0x0100: 2428 4c5b 4452 2453 272a 5e34 2f46 4e26 $(L[DR$S’*^4/FN&
0x0110: 282b 5846 4055 2530 1116 7312 0870 3641 (+XF@U%0..s..p6A
0x0120: 4141 3935 3431 4630 736c 0368 7433 3641 AA9541F0sl.ht36A
0x0130: 4141 3935 3431 4630 AA9541F0

6. Toolkit analysis
6 / [The State of the Internet] / Security Threat Advisory
• The decrypted payload consists of the following:
• Target IP address (4 bytes)
• Target port (2 bytes)
• Payload data
• DDoS flood: SYN (05) or DNS (04)
• If the command is for a DNS flood, the DNS query will be
placed after the target port
• Size of the payload for the attack

7. DDoS attack payloads
• Sample payload of the SYN flood attack traffic captured in
a controlled lab environment
7 / [The State of the Internet] / Security Threat Advisory
17:49:33.969933 IP 172.16.108.137.49020 > X.X.X.X.80: Flags [S], seq
3212631378:3212632377, win 65535, options [mss 1460,nop,nop,sackOK], length 999
0x0000: 4500 0417 bf7c 0000 8006 da46 ac10 6c89 E....|.....F..l.
0x0010: XXXX XXXX bf7c 1f90 bf7c dd52 0000 0000 .....|...|.R....
0x0020: 7002 ffff 663e 0000 0204 05b4 0101 0402 p...f>..........
... 0x00 filled ...
0x0400: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0410: 0000 0000 0000 00 .......

8. • Sample payload of DNS flood attack
DDoS attack payloads
12:14:48.274303 IP 172.16.108.137.18981 > X.X.X.X.53: UDP, length 40
0x0000: 4500 0044 4a25 0000 8011 5366 ac10 6c89 E..DJ%....Sf..l.
0x0010: XXXX XXXX 4a25 0035 0030 cedc 4a25 0120 ....J%.5.0..J%..
0x0020: 0001 0000 0000 0001 0765 7861 6d70 6c65 .........example
0x0030: 0363 6f6d 0000 0100 0100 0029 1000 0000 .com.......)....
0x0040: 0000 0000
8 / [The State of the Internet] / Security Threat Advisory

9. • Once a flood command is received from the C2, the malware
builds a AYN or DNS flood
Toolkit analysis
9 / [The State of the Internet] / Security Threat Advisory

10. • Function names build_iphdr and build_tcphdr are associated
with building the appropriate TCP/IP headers.
• Predefined data structures used include SIZE_TCP_H,
SIZE_IP_H with options
Recommended DDoS detection methods
10 / [The State of the Internet] / Security Threat Advisory

11. Download the XOR DDoS Security Threat Advisory for full
detection and removal recommendations
The report covers:
• Detailed explanation of threat
• Indicators of infection
• Payload decryption
• Execution paths
• Static characteristics
• Snort and YARA rules
• Foursteps for malware removal
Q3 2015 State of the Internet – Security Report
11 / [The State of the Internet] / Security Threat Advisory

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12 / [The State of the Internet] / Security Threat Advisory