Preface: People judge an issue depends on your point of view. A design flaw or limitation of product in normal view point will make people dissatisfy. It is annoying and blame the designer what he is doing, does he dreaming?
From hacker point of view, the flaw can become a backdoor.

Highlight: CVE-2019-1804 – Cisco Nexus 9000 Series Fabric Switches Application Centric Infrastructure Mode Default SSH Key Vulnerability

Vulnerability details: The vulnerability occurs because default SSH key pair that is present in all devices. By default, most SSH implementations (e.g., OpenSSH) allow users to configure their own authorized key files (placing a public key in an account so they can access it using a private key). If organizations don’t keep an up to date inventory of authorized keys and regularly review it, users or even attackers may place authorized keys in unexpected places for future access.

Attention: For user who purchase directly from Cisco but do not hold a Cisco service contract. Do not worry, you should provides the product serial number and CVE reference number to Cisco as evidence of entitlement to a free upgrade. Besides, ther are many security update this week, please contact your cisco partner for update details.

Reference: Official announcement – https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190501-nexus9k-sshkey

Preface: In modern smart world, efficiency is the key words. Do we need that?

Background: Memcached is a decentralized cache memory system. Use Memcached can improve database performance. Redis and Memcached are popular today. The reason is that both are the open-source products. And they can boost up database performance. Redis and Memcached are both in-memory data storage systems.

Vulnerability details: A vulnerability in Memcached could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.
The vulnerability exists because the lru mode and lru temp_ttl commands, as implemented in the memcached.c source code file, do not properly perform memory operations, which could result in a NULL pointer dereference memory operation error. NULL pointer dereference erros are common in C/C++ languages. Pointer is a programming language data type that references a location in memory. Once the value of the location is obtained by the pointer, this pointer is considered dereferenced.

Remedy: Remediation at the following links – https://github.com/memcached/memcached/commit/d35334f368817a77a6bd1f33c6a5676b2c402c02

Preface: IT world can’t without DHCP function! It looks like public vehicle in our daily life.

Background: dhcpcd is a DHCP and DHCPv6 client. It is currently the most feature-rich open source DHCP client.

Vulnerabilities Details:
One of the vulnerabilities exists because the dhcp6_findna() function (src / dhcp6.c source code file) does not correctly handle reading specific addresses.
The idea of exploiting this vulnerability involves modifying ebp to point to a part of the buffer where a return address can be read from, and at the same time, points to the payload within the same buffer. We so called 1-byte buffer overflows.R

Remedy:

DHCPv6 – https://roy.marples.name/git/dhcpcd.git/commit/?id=8d11b33f6c60e2db257130fa383ba76b6018bcf6
DHCP – https://roy.marples.name/projects/dhcpcd

Preface: On April 17, 2019, the National Information Security Vulnerability Sharing Platform (CNVD) recorded the Oracle WebLogic wls9-async deserialization remote command execution vulnerability reported by China Minsheng Banking Co., Ltd.

Synopsis: There are reports of this vulnerability being actively exploited in the wild in April 2019.

Vulnerability details:
CVE-2019-2725 – A vulnerability has been discovered in the Oracle WebLogic components (WLS9_ASYNC and WLS-WSAT) that could allow for remote code execution. But this vulnerability seems not a zero-day. The similar vulnerability has been found in 2017.
Perhaps attached diagram can provides hints to you.

Non official remedy:
Option 1: Find and delete ws9_ async_response.war, wIs-wsat.war and restart the Weblogic service.

Option 2: Control access to URLs for /_async/* and /wls-wsat/* (note) paths through access policy control.

Official announcement: https://www.oracle.com/technetwork/security-advisory/alert-cve-2019-2725-5466295.html

Preface: Error handling in PHP is still primitive. However you can code your way around most problems.

Synopsis: From technical point of view, a JPEG file with malicious EXIF data, and a PHP code that executes it. This PHP code can be easily inserted into any other PHP file found in the server, probably not noticed as malicious in a quick check.

Vulnerability details:
PHP EXIF exif_iif_add_tag Heap Buffer Overflow Vulnerability – A successful exploit could allow the attacker to access sensitive information, which could be used to conduct additional attacks.
PHP EXIF exif_process_IFD_in_MAKERNOTE Heap Buffer Overflow Vulnerability – A successful exploit could allow the attacker to access sensitive information, which could be used to conduct further attacks.

Remedy: PHP Project has released software updates, please refer url: https://php.net/downloads.php

Preface: Operating system · Linux, NetBSD, FreeBSD, OpenBSD, macOS, Windows · Type · DNS server · License · Mozilla Public License (ISC license before 9.11). Website, www.isc.org/downloads/bind. BIND is the most widely used Domain Name System (DNS).

Alert: A design limitation of BIND let remote attacker could exploit these vulnerabilities to cause a denial-of-service condition. Official details shown as below:

CVE-2019-6467: https://kb.isc.org/docs/cve-2019-6467
CVE-2019-6468: https://kb.isc.org/docs/cve-2019-6468
CVE-2018-5743: https://kb.isc.org/docs/cve-2018-5743

Technical highlight: CVE-2018-5743 flaw impact the limiting simultaneous TCP clients is ineffective. It potentially lead to exhaustion of all available free file descriptors on that system. That is, when you open a file, the operating system creates an entry to represent that file and store the information about that opened file. So if there are 50 files opened in your OS then there will be 50 entries in OS (somewhere in kernel). So it may potential trigger additional unknown vulnerability.

Preface: Kiss O’Death Packet and Other NTP Vulnerabilities potentially turn back the Internet’s Clocks and causes unpredictable problem.

NTP vulnerability – historical record: There was a loophole in 2013,, the attack relies on the exploitation of the ‘monlist’ feature of NTP, as described in CVE-2013-5211, which is enabled by default on older NTP-capable devices. This command causes a list of the last 600 IP addresses which connected to the NTP server to be sent to the victim.

CVE-2019-11331 vulnerability details: The vulnerability is due to improper use of UDP port 123 by the affected software. Threat actor can make a malicious packet input to the targeted system. A successful exploit could allow the attacker to conduct an off-path attack.

Remedy: NTP.org had not released a security advisory. Stay tuned.

Preface: An IT ecosystem is “the network of organizations that drives the creation and delivery of information technology products and services.

About urllib3: Much of the Python ecosystem already uses urllib. It brings additional features that are missing from the Python standard libraries. For instance – Client-side SSL/TLS verification, Helpers for retrying requests and dealing with HTTP redirects,……

Vulnerability details: A vulnerability in urllib3 could allow an unauthenticated, remote attacker to bypass security restrictions on a targeted system.

Findings: The vulnerability exists because the affected software mishandles CA certificates that are related to the use of the ssl_context, ca_certs, or ca_certs_dir parameters.

Remedy: Software updates at the following link: https://github.com/urllib3/urllib3/releases