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New research has found that the CONTINUATION frame in the HTTP/2 protocol can be exploited to conduct denial-of-service (DoS) attacks. The technique has been codenamed  HTTP/2 CONTINUATION Flood  by security researcher Bartek Nowotarski, who reported the issue to the CERT Coordination Center (CERT/CC) on January 25, 2024. "Many HTTP/2 implementations do not properly limit or sanitize the amount of CONTINUATION frames sent within a single stream," CERT/CC  said  in an advisory on April 3, 2024. "An attacker that can send packets to a target server can send a stream of CONTINUATION frames that will not be appended to the header list in memory but will still be processed and decoded by the server or will be appended to the header list, causing an out of memory (OOM) crash." Like in HTTP/1, HTTP/2 uses header fields within requests and responses. These  header fields  can comprise header lists, which in turn, are serialized and broken into  header blocks . The head

Ivanti has released security updates to address four security flaws impacting Connect Secure and Policy Secure Gateways that could result in code execution and denial-of-service (DoS). The list of flaws is as follows - CVE-2024-21894  (CVSS score: 8.2) - A heap overflow vulnerability in the IPSec component of Ivanti Connect Secure (9.x, 22.x) and Ivanti Policy Secure allows an unauthenticated malicious user to send specially crafted requests in order to crash the service thereby causing a DoS attack. In certain conditions, this may lead to execution of arbitrary code. CVE-2024-22052  (CVSS score: 7.5) - A null pointer dereference vulnerability in IPSec component of Ivanti Connect Secure (9.x, 22.x) and Ivanti Policy Secure allows an unauthenticated malicious user to send specially crafted requests in order to crash the service thereby causing a DoS attack. CVE-2024-22053  (CVSS score: 8.2) - A heap overflow vulnerability in the IPSec component of Ivanti Connect Secure (9.x, 2

For years, securing a company's systems was synonymous with securing its "perimeter." There was what was safe "inside" and the unsafe outside world. We built sturdy firewalls and deployed sophisticated detection systems, confident that keeping the barbarians outside the walls kept our data and systems safe. The problem is that we no longer operate within the confines of physical on-prem installations and controlled networks. Data and applications now reside in distributed cloud environments and data centers, accessed by users and devices connecting from anywhere on the planet. The walls have crumbled, and the perimeter has dissolved, opening the door to a new battlefield: identity . Identity is at the center of what the industry has praised as the new gold standard of enterprise security: "zero trust." In this paradigm, explicit trust becomes mandatory for any interactions between systems, and no implicit trust shall subsist. Every access request, regardless of its origin,

A novel denial-of-service (DoS) attack vector has been found to target application-layer protocols based on User Datagram Protocol (UDP), putting hundreds of thousands of hosts likely at risk. Called  Loop DoS attacks , the  approach  pairs "servers of these protocols in such a way that they communicate with each other indefinitely," researchers from the CISPA Helmholtz-Center for Information Security said. UDP, by design, is a  connectionless protocol  that does not validate source IP addresses, making it susceptible to IP spoofing. Thus, when attackers forge several UDP packets to include a victim IP address, the destination server responds to the victim (as opposed to the threat actor), creating a reflected denial-of-service (DoS) attack. The latest study found that certain implementations of the UDP protocol, such as DNS, NTP, TFTP, Active Users, Daytime, Echo, Chargen, QOTD, and Time, can be weaponized to create a self-perpetuating attack loop. "It pairs two

Atlassian and the Internet Systems Consortium (ISC) have disclosed several security flaws impacting their products that could be exploited to achieve denial-of-service (DoS) and remote code execution. The Australian software services provider  said  that the four high-severity flaws were fixed in new versions shipped last month. This includes - CVE-2022-25647  (CVSS score: 7.5) - A deserialization flaw in the Google Gson package impacting Patch Management in Jira Service Management Data Center and Server CVE-2023-22512  (CVSS score: 7.5) - A DoS flaw in Confluence Data Center and Server CVE-2023-22513  (CVSS score: 8.5) - A RCE flaw in Bitbucket Data Center and Server CVE-2023-28709  (CVSS score: 7.5) - A DoS flaw in Apache Tomcat server impacting Bamboo Data Center and Server The flaws have been addressed in the following versions - Jira Service Management Server and Data Center (versions 4.20.25, 5.4.9, 5.9.2, 5.10.1, 5.11.0, or later) Confluence Server and Data Center (v

Networking equipment maker Zyxel has released patches for a critical security flaw in its firewall devices that could be exploited to achieve remote code execution on affected systems. The issue, tracked as  CVE-2023-28771 , is rated 9.8 on the CVSS scoring system. Researchers from TRAPA Security have been credited with reporting the flaw. "Improper error message handling in some firewall versions could allow an unauthenticated attacker to execute some OS commands remotely by sending crafted packets to an affected device," Zyxel  said  in an advisory on April 25, 2023. Products impacted by the flaw are - ATP (versions ZLD V4.60 to V5.35, patched in ZLD V5.36) USG FLEX (versions ZLD V4.60 to V5.35, patched in ZLD V5.36) VPN (versions ZLD V4.60 to V5.35, patched in ZLD V5.36), and ZyWALL/USG (versions ZLD V4.60 to V4.73, patched in ZLD V4.73 Patch 1) Zyxel has also  addressed  a high-severity post-authentication command injection vulnerability affecting select firewa

Cisco on Wednesday rolled out patches to address  three security flaws  affecting its products, including a high-severity weakness disclosed in NVIDIA Data Plane Development Kit (MLNX_DPDK) late last month. Tracked as  CVE-2022-28199  (CVSS score: 8.6), the vulnerability stems from a lack of proper error handling in DPDK's network stack, enabling a remote adversary to trigger a denial-of-service (DoS) condition and cause an impact on data integrity and confidentiality. "If an error condition is observed on the device interface, the device may either reload or fail to receive traffic, resulting in a denial-of-service (DoS) condition," Cisco  said  in a notice published on September 7. DPDK  refers to a set of libraries and optimized network interface card (NIC) drivers for fast packet processing, offering a framework and common API for high-speed networking applications. Cisco said it investigated its product lineup and determined the following services to be affecte

Networking equipment maker Cisco has released security updates to address three high-severity vulnerabilities in its products that could be exploited to cause a denial-of-service (DoS) condition and take control of affected systems. The first of the three flaws,  CVE-2022-20783  (CVSS score: 7.5), affects Cisco TelePresence Collaboration Endpoint (CE) Software and Cisco RoomOS Software, and stems from a lack of proper input validation, allowing an unauthenticated, remote attacker to send specially crafted traffic to the devices. "A successful exploit could allow the attacker to cause the affected device to either reboot normally or reboot into maintenance mode, which could result in a DoS condition on the device," the company  noted  in an advisory. Credited with discovering and reporting the flaw is the U.S. National Security Agency (NSA). The issue has been addressed in Cisco TelePresence CE Software versions 9.15.10.8 and 10.11.2.2. CVE-2022-20773  (CVSS score: 7.5),

SonicWall has released security updates to contain a critical flaw across multiple firewall appliances that could be weaponized by an unauthenticated, remote attacker to execute arbitrary code and cause a denial-of-service (DoS) condition. Tracked as  CVE-2022-22274  (CVSS score: 9.4), the issue has been described as a stack-based buffer overflow in the web management interface of SonicOS that could be triggered by sending a specially crafted HTTP request, leading to remote code execution or DoS. The flaw impacts 31 different SonicWall Firewall devices running versions 7.0.1-5050 and earlier, 7.0.1-R579 and earlier, and 6.5.4.4-44v-21-1452 and earlier. ZiTong Wang of Hatlab has been credited with reporting the issue. The network security company  said  it's not aware of any instance of active exploitation in the wild leveraging the weakness, and that no proof-of-concept (PoC) or malicious use of the vulnerability has been publicly reported to date. That said, users of the a

Apple on Wednesday rolled out software updates for iOS and iPadOS to remediate a persistent  denial-of-service (DoS) issue  affecting the HomeKit smart home framework that could be potentially exploited to launch ransomware-like attacks targeting the devices. The iPhone maker, in its  release notes  for iOS and iPadOS 15.2.1, termed it as a "resource exhaustion issue" that could be triggered when processing a maliciously crafted HomeKit accessory name, adding it addressed the bug with improved validation. The so-called "doorLock" vulnerability, tracked as CVE-2022-22588, affects HomeKit, the software API for connecting smart home devices to iOS applications. Should it be successfully exploited, iPhones and iPads can be sent into a crash spiral simply by changing the name of a HomeKit device to a string larger than 500,000 characters and tricking the target into accepting a malicious Home invitation. Even worse, since HomeKit device names are backed up to iClou

The maintainers of OpenSSL have released a fix for two high-severity security flaws in its software that could be exploited to carry out denial-of-service (DoS) attacks and bypass certificate verification. Tracked as CVE-2021-3449 and CVE-2021-3450 , both the  vulnerabilities  have been resolved in an update (version OpenSSL 1.1.1k) released on Thursday. While CVE-2021-3449 affects all OpenSSL 1.1.1 versions, CVE-2021-3450 impacts OpenSSL versions 1.1.1h and newer. OpenSSL is a software library consisting of cryptographic functions that implement the Transport Layer Security protocol with the goal of securing communications sent over a computer network. According to an advisory published by OpenSSL, CVE-2021-3449 concerns a potential DoS vulnerability arising due to NULL pointer dereferencing that can cause an OpenSSL TLS server to crash if in the course of renegotiation the client transmits a malicious "ClientHello" message during the  handshake  between the server and

Cisco yesterday released security patches for two high-severity vulnerabilities affecting its IOS XR software that were found exploited in the wild a month ago. Tracked as CVE-2020-3566 and CVE-2020-3569 , details for both zero-day unauthenticated DoS vulnerabilities were made public by Cisco late last month when the company found hackers actively exploiting Cisco IOS XR Software that is installed on a range of Cisco's carrier-grade and data center routers. Both DoS vulnerabilities resided in Cisco IOS XR Software's Distance Vector Multicast Routing Protocol (DVMRP) feature and existed due to incorrect implementation of queue management for Internet Group Management Protocol (IGMP) packets on affected devices. IGMP is a communication protocol typically used by hosts and adjacent routers to efficiently use resources for multicasting applications when supporting streaming content such as online video streaming and gaming. "These vulnerabilities affect any Cisco device th

If your web-server runs on Apache, you should immediately install the latest available version of the server application to prevent hackers from taking unauthorized control over it. Apache recently fixed multiple vulnerabilities in its web server software that could have potentially led to the execution of arbitrary code and, in specific scenarios, even could allow attackers to cause a crash and denial of service. The flaws, tracked as CVE-2020-9490, CVE-2020-11984, CVE-2020-11993, were uncovered by Felix Wilhelm of Google Project Zero, and have since been addressed by the Apache Foundation in the latest version of the software ( 2.4.46 ). The first of the three issues involve a possible remote code execution vulnerability due to a buffer overflow with the "mod_uwsgi" module (CVE-2020-11984), potentially allowing an adversary to view, change, or delete sensitive data depending on the privileges associated with an application running on the server. "[A] Malici

Citrix yesterday issued new security patches for as many as 11 security flaws that affect its Citrix Application Delivery Controller (ADC), Gateway, and SD-WAN WAN Optimization edition (WANOP) networking products. Successful exploitation of these critical flaws could let unauthenticated attackers perform code injection, information disclosure, and even denial-of-service attacks against the gateway or the authentication virtual servers . Citrix confirmed that the aforementioned issues do not impact other virtual servers, such as load balancing and content switching virtual servers. Among the affected Citrix SD-WAN WANOP appliances include models 4000-WO, 4100-WO, 5000-WO, and 5100-WO. The networking vendor also reiterated that these vulnerabilities were not connected to a previously fixed zero-day NetScaler flaw (tagged as CVE-2019-19781 ) that allowed bad actors to perform arbitrary code execution even without proper authentication. It also said there's no evidence

A critical security vulnerability has been discovered and fixed in the popular open-source Exim email server software, which could allow a remote attacker to simply crash or potentially execute malicious code on targeted servers. Exim maintainers today released an urgent security update— Exim version 4.92.3 —after publishing an early warning two days ago, giving system administrators an early head-up on its upcoming security patches that affect all versions of the email server software from 4.92 up to and including then-latest version 4.92.2. Exim is a widely used, open source mail transfer agent (MTA) developed for Unix-like operating systems like Linux, Mac OSX or Solaris, which runs almost 60 percent of the Internet's email servers today for routing, delivering and receiving email messages. This is the second time in this month when the Exim maintainers have released an urgent security update. Earlier this month, the team patched a critical remote code execution flaw (

Various implementations of HTTP/2 , the latest version of the HTTP network protocol, have been found vulnerable to multiple security vulnerabilities affecting the most popular web server software, including Apache, Microsoft's IIS, and NGINX. Launched in May 2015, HTTP/2 has been designed for better security and improved online experience by speeding up page loads. Today, over hundreds of millions of websites, or some 40 percent of all the sites on the Internet, are running using HTTP/2 protocol. A total of eight high-severity HTTP/2 vulnerabilities , seven discovered by Jonathan Looney of Netflix and one by Piotr Sikora of Google, exist due to resource exhaustion when handling malicious input, allowing a client to overload server's queue management code. The vulnerabilities can be exploited to launch Denial of Service (DoS) attacks against millions of online services and websites that are running on a web server with the vulnerable implementation of HTTP/2 , knocking

Samba maintainers have just released new versions of their networking software to patch two critical vulnerabilities that could allow unprivileged remote attackers to launch DoS attacks against servers and change any other users' passwords, including admin's. Samba is open-source software (re-implementation of SMB networking protocol) that runs on the majority of operating systems available today, including Windows, Linux, UNIX, IBM System 390, and OpenVMS. Samba allows non-Windows operating systems, like GNU/Linux or Mac OS X, to share network shared folders, files, and printers with Windows operating system. The denial of service vulnerability, assigned CVE-2018-1050 , affects all versions of Samba from 4.0.0 onwards and could be exploited "when the RPC spoolss service is configured to be run as an external daemon." "Missing input sanitization checks on some of the input parameters to spoolss RPC calls could cause the print spooler service to crash.

Cybercriminals have figured out a way to abuse widely-used Memcached servers to launch over 51,000 times powerful DDoS attacks than their original strength, which could result in knocking down of major websites and Internet infrastructure. In recent days, security researchers at Cloudflare , Arbor Networks , and Chinese security firm Qihoo 360 noticed that hackers are now abusing "Memcached" to amplify their DDoS attacks by an unprecedented factor of 51,200. Memcached is a popular open-source and easily deployable distributed caching system that allows objects to be stored in memory and has been designed to work with a large number of open connections. Memcached server runs over TCP or UDP port 11211. The Memcached application has been designed to speed up dynamic web applications by reducing stress on the database that helps administrators to increase performance and scale web applications. It's widely used by thousands of websites, including Facebook, Flickr,

A simple yet serious application-level denial of service (DoS) vulnerability has been discovered in WordPress CMS platform that could allow anyone to take down most WordPress websites even with a single machine—without hitting with a massive amount of bandwidth, as required in network-level DDoS attacks to achieve the same. Since the company has denied patching the issue, the vulnerability ( CVE-2018-6389 ) remains unpatched and affects almost all versions of WordPress released in last nine years, including the latest stable release of WordPress (Version 4.9.2). Discovered by Israeli security researcher Barak Tawily , the vulnerability resides in the way " load-scripts.php ," a built-in script in WordPress CMS, processes user-defined requests. For those unaware, load-scripts.php file has only been designed for admin users to help a website improve performance and load page faster by combining (on the server end) multiple JavaScript files into a single request. Howe

As part of its "October Patch Tuesday," Microsoft has today released a large batch of security updates to patch a total of 62 vulnerabilities in its products, including a severe MS office zero-day flaw that has been exploited in the wild. Security updates also include patches for Microsoft Windows operating systems, Internet Explorer, Microsoft Edge, Skype, Microsoft Lync and Microsoft SharePoint Server. Besides the MS Office vulnerability, the company has also addressed two other publicly disclosed (but not yet targeted in the wild) vulnerabilities that affect the SharePoint Server and the Windows Subsystem for Linux. October patch Tuesday also fixes a critical Windows DNS vulnerability that could be exploited by a malicious DNS server to execute arbitrary code on the targeted system. Below you can find a brief technical explanation of all above mentioned critical and important vulnerabilities. Microsoft Office Memory Corruption Vulnerability (CVE-2017-11826) T

Yes, you only need a single laptop with a decent internet connection, rather a massive botnet, to launch overwhelming denial of service (DoS) attacks in order to bring down major Internet servers and modern-day firewalls. Researchers at TDC Security Operations Center have discovered a new attack technique that lone attackers with limited resources (in this case, a laptop and at least 15Mbps of bandwidth) can use to knock large servers offline. Dubbed a BlackNurse attack or the low-rate " Ping of Death " attack, the technique can be used to launch several low-volume DoS attacks by sending specially formed Internet Control Message Protocol (ICMP) packets, or 'pings' that overwhelm the processors on server protected by firewalls from Cisco, Palo Alto Networks, among others. ICMP is a protocol used by routers and other networking devices to send and receive error messages. According to a technical report [ PDF ] published this week, the BlackNurse attack is mo