We are living on earth. The human being ancestor went through different generations of reforms. As a result modern civilization today. The foundation of civilization build by different elements and objects. A major element named logic, it structure cause and effect. Above definition involve successful factor of result. However some sort of things happen on earth looks mystery. Quote an example, Friday the 13th is considered an unlucky day in Western superstition. From scientific view point, such superstition it doesn’t make sense and no background factor support. By coincidence when you go to cosmopolitan city like Chicago or New York. You couldn’t found 13th Floor on escalator? Even though without scientific factor support this superstition whereas No.13th or Black Friday bring us psychological impact. We continue this discussion but our focus will go to cyber security. Up to this point, you might have question to ask? Why do we spend time on preface mention superstition topic?

Do you remember Jerusalem virus?

A virus first detected in Jerusalem, in 13th October 1987 (Black Friday). This virus hook itself on MS DOS services and capable run malware function. But internet communicate services not available at 80’s. How does it work? The virus program contains one destructive payload that is set to go off on black Friday (Friday the 13th). This is the 1st time let IT guru know a cyber attack schedule Friday the 13th Jan 2016. Below is the source code highlight for reference:

mov ah,02Ah             ; Get system data
int 021h
mov byte cs:[zap],00H
cmp cx,07C3h            ; CX->Year, 7C4h=1987
jz done                 ; Do nothing if1987
cmp al,05h              ; AL->Day,05h=Friday
jnz otherpload          ; No zap if not Fri
cmp dl,00h              ; DL->Date, 00h=13
jnz otherpload          ; No zap if not 13th
inc byte cs:[zap]       ; Else turn on ZapFlag
jmp done
nop

Attack concept and idea – take advantage of the computer instruction set design limitation. For more details, please see below:

1. If the interrupt flag (IF) is set (=1) then external hardware can initiate an interrupt via the INTR input of the microprocessor.
2. If IF flag is clear (=) then the external device cannot initiate an interrupt.

Jerusalem code itself hooks into interrupt processing and other low level DOS services. This type of infection technique looks similar of the privileges escalation method run by malware today!

Keep away from anything labeled thirteen

Unfortunately, cyber incident occurs in 2013, coincidence that magic number thirteen was involved in the naming convention scheme. It is a crypto TLS vulnerability. Before we discuss what is lucky 13. Let’s do a quick review of TLS & SSL/TLS protocol architecture in below info graphic diagram.

Overview of TLS & SSL/TLS protocol architecture

 

As we know, there are total 4 types of SSL attack recently.

• Beast attack
• Crime attack
• Lucky 13 attack
• RC4 attack

To be honest, lucky 13 not equivalent to the meaning of his name. It is a cryptographic timing attack against implementations of the Transport Layer Security (TLS) protocol originally.

What is timing attack? (see below)

The attack allows a man-in-the-middle attacker to recover plaintext from a TLS/DTLS connection when CBC-mode (cipher-block chaining) encryption is used. Man-in-the-middle timing attack against TLS that exploits the interaction between how the protocol implements AES in CBC mode for encryption, and HMAC-SHA1 for authentication.

CVE-2013-0169 – The TLS protocol 1.1 and 1.2 and the DTLS protocol 1.0 and 1.2, as used in OpenSSL, OpenJDK, PolarSSL, and other products, do not properly consider timing side-channel attacks on a MAC check requirement during the processing of malformed CBC padding, which allows remote attackers to conduct distinguishing attacks and plaintext-recovery attacks via statistical analysis of timing data for crafted packets.

Predict more security bug in future, it is a fundamental design limitation so called MAC then encrypt

Encryption algorithm tried to apply it to TCP/IP but the model does not match well TCP/IP. Some things don’t fit in the layers, and SSL/TLS is one of them.

D(TLS) encryption process (see below):

• SSL/TLS uses an underlying transport medium that provides a bidirectional stream of bytes. That would put it somewhere above layer 4.
• SSL/TLS organizes data as records, that may contain, in particular, handshake messages. Handshake messages look like layer 5. This would put SSL/TLS at layer 6 or 7.
• However, what SSL/TLS conveys is “application data”, which is, in fact, a bidirectional stream of bytes. Applications that use SSL/TLS really use it as a transport protocol. They then use their own data representation and messages and semantics within that “application data”. Therefore, SSL/TLS cannot be, in the OSI model, beyond layer 4.

The Lucky13 attack triggered a series of TLS technical concerns . Yet another Padding Oracle vulnerability found in May 2016 (see below)

Padding oracle in AES-NI CBC MAC check (CVE-2016-2107)
======================================================

Severity: High

A MITM attacker can use a padding oracle attack todecrypt traffic
when the connection uses an AES CBC cipher and the server support
AES-NI.

This issue was introduced as part of the fix for Lucky 13 padding
attack (CVE-2013-0169). The padding check was rewritten to be inconstanttimeby making sure that always the same bytesarereadand
compared against either the MAC or padding bytes. But it no longer
checked that there was enough datato have both the MAC and padding
bytes.

OpenSSL 1.0.2users should upgradeto1.0.2h
OpenSSL 1.0.1users should upgradeto1.0.1t

This issue was reported to OpenSSL on13th of April 2016by Juraj
Somorovsky using TLS-Attacker. The fix was developed by Kurt Roeckx
of the OpenSSL development team.

Interim summary:

A good practise on web server to mitigate the risk:

Control requirement on web server

• Do not configure wild card certificates
• Certificate to be signed by trusted certificate authority (CA)
• Ensure session cookies have “secure=true” flag set
• Ensure HSTS header is set for domain and sub domain

http://img.photobucket.com/albums/v704/chanpicco/chanpicco071/SS7-ASN1-Flaw_zpslcpchclx.jpg

Preface

People might questions leonardo Da Vinci if he still alive. Why did he choose this woman became mona lisa? Since nobody could explain on behalf of him. But strongly believe that this is the original design.

Linux are everywhere today, in workstation, servers, mobile devices and IoT devices. On the other hand, the culture of modern world relies on electronic communications system. Therefore network communication protocol especially TCP/IP protocol and Signaling System 7 are the major elements in nowadays world.

Recall historical data of specific elements (quick & dirty)

1. ASN.1

Originally defined in 1984 as part of CCITT X.409:1984

Design objective:

i. Overcome how different computer systems transmit data
ii. Model parameters exchanged between application entities

 

2. Signalling System 7

It was developed in 1975

Design objective

i. SS7 controls telephone calls, both wired and wireless, through the use of a control signal that is separate from the actual voice circuit.

ii. It allows phone networks to exchange the information needed for passing calls and text messages between each other.

3. TCP/IP version 4

The first version of this predecessor of modern TCP was written in 1973

Design objective

i. A set of general design guidelines and implementations of specific networking protocols to enable computers to communicate over networks.

ii. TCP/IP provides end-to-end connectivity specifying how data should be formatted, addressed, transmitted, routed and received at the destination.

Flaws found as of today

TCP/IP version 4 (CVE-2016-5696)

The difficult part for hacker taking over TCP connection is to guess the source port of the client and the current sequence number. A group of researchers found that open a connection to the server and send with the source of the attacker as much “RST” handshake packets with the wrong sequence mixed with a few spoofed packets. By counting how much “challenge ACK” handshake packet get returned to the attacker side.  Attacker might knowing the rate limit one can infer how much of the spoofed packets resulted in a challenge ACK to the spoofed client and thus how many of the guesses where correct. This way can quickly narrow down which values of port and sequence are correct.

http://img.photobucket.com/albums/v704/chanpicco/chanpicco071/ninja-anima-ver2_zpsoonzpftm.gif

Interim solution apply to Linux environment

Linux are everywhere today, in workstation, servers, mobile devices and IoT devices. Append the following to /etc/sysctl.conf:

net.ipv4.tcp_challenge_ack_limit = 999999999

Use “sysctl -p” to activate this feature

Flaw found in ASN.1 compiler

For more details, please see below:

https://www.linkedin.com/pulse/flaw-found-communications-industry-yet-determined-1-picco

Interim solution: unavailable

Current status: The extent of the vulnerability has yet to be determined, IT folks this vulnerability looks critical. It is hard to imagine what’s the impact at this moment. We keep our eyes open see whether a remediation will be announced by the telecommunication providers?

SS7 Vulnerability

A proof of concept shown that attacker could use the telephone network to access the voice data of a mobile phone, find its location and collect other information. Hacker able to manipulating USSD commands to spoof financial transactions such as the authorization of purchases or the transfer of funds between accounts.

The hacks exploit the SS7 vulnerability by tricking the telecom network believing the attacker’s phone has the same number as the victim’s phone. We know that hackers can hijack whatsApp and telegram via ss7. A vulnerability found on 2008.

Interim solution

Mobile phone network services provider has employed security experts to perform analysis of the SS7 systems in use to try and prevent unauthorised access.

For additional information details, please refer below:

SS7 hack explained: what can you do about it?

http://img.photobucket.com/albums/v704/chanpicco/chanpicco071/OSI-vs-SS7_zpsk76izco4.gif

How to protect your IT premises in regards to above flaws?

For weakness of TCP/IP protocol, the IP version 6 able to resolve design limitation of sequence number. In the long run, it is recommend IT team get rid of IP version 4. However the truth is that v4 and v6 are mixed mode in nowadays IT world.

The most headache topics are the ANS.1 complier flaw and Signalling system 7 vulnerability. For SS7 vulnerability, since those item of works (remediation and mitigation) are relies on Telecommunication service providers. Mobile phone network services provider employing security experts to perform analysis of the SS7 systems in use to try and prevent unauthorised access. For text messages, avoiding using SMS. As far as we know, whatsapp communication is being encrypted today!

How’s the status of ASN.1 compiler right now?

About SS7 vulnerability information update:

Nokia safeguards network operations with new security features in Sep 2015. The features consisting of Signaling Guard and Security Assessment service, detects and prevents attacks that exploit vulnerabilities in the SS7 protocol. For more details. Please refer to url below:

http://company.nokia.com/en/news/press-releases/2015/09/03/nokia-networks-safeguards-network-operations-with-two-new-security-launches-networksperform

About  SS7 vulnerability incident found and reported by German newspaper media on May 2017:

German newspaper (Süddeutsche Zeitung) reported that that hackers relied on SS7 attacks flaw as a backdoor. The vulnerability allow bypass two-factor authentication (2FA) systems to conduct unauthorized wire transfers.

http://www.sueddeutsche.de/digital/it-sicherheit-schwachstelle-im-mobilfunknetz-kriminelle-hacker-raeumen-konten-leer-1.3486504