Tag Archive for: Schwachstellen-Management

Joseph Lee

CVE-2024-31497: PuTTY Forfeits Client ECDSA Private Keys

Public-key cryptography underpins enterprise network security and thus, securing the confidentiality of private keys is one of the most critical IT security challenges for preventing unauthorized access and maintaining the confidentiality of data. While Quantum Safe Cryptography (QSC) has emerged as a top concern for the future, recent critical vulnerabilities like CVE-2024-3094 (CVSS 10) in XZ Utils and the newly disclosed CVE-2024-31497 (CVSS 8.8) in PuTTY are here and now – real and present dangers.

Luckily, the XZ Utils vulnerability was caught before widespread deployment into Linux stable release branches. However, by comparison, CVE-2024-31497 in PuTTY represents a much bigger threat than the aforementioned vulnerability in XZ Utils despite its lower CVSS score. Let’s examine the details to understand why and review Greenbone’s capabilities for detecting known cryptographic vulnerabilities.

A Primer On Public Key Authentication

Public-key infrastructure (PKI) is fundamental to a wide array of digital trust services such as Internet and enterprise LAN authentication, authorization, privacy, and application security. For public-key authentication both the client and server each need a pair of interconnected cryptographic keys: a private key, and a public key. The public keys are openly shared between the two connecting parties, while the private keys are used to digitally sign messages sent between them, and the associated public keys are used to decrypt those messages. This is how each party fundamentally verifies the other’s identity and how a single symmetric key is agreed upon for continuous encrypted communication with an optimal connection speed.

In the client-server model of communication, if the client’s private key is compromised, an attacker can potentially authenticate to any resources that honor it. If the server’s private key is compromised, an attacker can potentially spoof the server’s identity and conduct Adversary-in-the-Middle (AitM) attacks.

CVE-2024-31497 Affects All Versions of PuTTY

CVE-2024-31497 in the popular Windows SSH client PuTTY allows an attacker to recover a client’s NIST P-521 secret key by capturing and analyzing approximately 60 digital signatures due to biased ECDSA nonce generation. As of NIST SP-800-186 (2023) NIST ECDSA P-521 keys are still classified among those offering the highest cryptographic resilience and recommended for use in various applications, including SSL/TLS and Secure Shell (SSH) applications. So, a vulnerability in an application’s implementation of ECDSA P-521 authentication is a serious disservice to IT teams who have otherwise applied appropriately strong encryption standards.

In the case of CVE-2024-31497, the client’s digital signatures are subject to cryptanalysis attacks that can reveal the private key. While developing an exploit for CVE-2024-31497 is a highly skilled endeavor requiring expert cryptographers and computer engineers, a proof-of-concept (PoC) code has been released publically, indicating a high risk that CVE-2024-31497 may be actively exploited by even low skilled attackers in the near future.

Adversaries could capture a victim’s signatures by monitoring network traffic, but signatures may already be publicly available if PuTTY was used for signing commits of public GitHub repositories using NIST ECDSA P-521 keys. In other words, adversaries may be able to find enough information to compromise a private key from publicly accessible data, enabling supply-chain attacks on a victim’s software.

CVE-2024-31497 affects all versions of PuTTY after 0.68 (early 2017) before 0.81 and affects FileZilla before 3.67.0, WinSCP before 6.3.3, TortoiseGit before 2.15.0.1, and TortoiseSVN through 1.14.6, and potentially other products.

On the bright side, Greenbone is able to detect the various vulnerable versions of PuTTY with multiple Vulnerability Tests (VTs). Greenbone can identify Windows Registry Keys that indicate a vulnerable version of PuTTY is present on a scan target, and has additional tests for PuTTY for Linux [1][2][3], FileZilla [4][5], and versions of Citrix Hypervisor/XenServer [6] susceptible to CVE-2024-31497.

Greenbone Protects Against Known Encryption Flaws

Encryption flaws can be caused by weak cryptographic algorithms, misconfigurations, and flawed implementations of an otherwise strong encryption algorithm, such as the case of CVE-2024-31497. Greenbone includes over 6,500 separate Network Vulnerability Tests (NVTs) and Local Security Checks (LSCs) that can identify all types of cryptographic flaws. Some examples of cryptographic flaws that Greebone can detect include:

  • Application Specific Vulnerabilities: Greenbone can detect over 6500 OS and application specific encryption vulnerabilities for which CVEs have been published.
  • Lack Of Encryption: Unencrypted remote authentication or other data transfers, and even unencrypted local services pose a significant risk to sensitive data when attackers have gained an advantageous position such as the ability to monitor network traffic.
  • Support For Weak Encryption Algorithms: Weak encryption algorithms or cipher suites no longer provide strong assurances against cryptanalysis attacks. When they are in use, communications are at higher risk of data theft and an attacker may be able to forge communication to execute arbitrary commands on a victim’s system. Greenbone includes more than 1000 NVTs to detect remote services using weak encryption algorithms.
  • Non-Compliant TLS Settings And HTTPS Security Headers: Greenbone has NVTs to detect when HTTP Strict Transport Security (HSTS) is not configured and verify web-server TLS policy.

Summary

SSH public-key authentication is widely considered one of the most – if not the most secure remote access protocol, but two recent vulnerabilities have put this critical service in the spotlight. CVE-2024-3094, a trojan planted in XZ Utils found its way into some experimental Linux repositories before it’s discovery, and CVE-2024-31497 in PuTTY allows a cryptographic attack to extract a client’s private key if an attacker can obtain roughly 60 digital signatures.

Greenbone can detect emerging threats to encryption such as CVE-2024-31497 and includes over 6,500 other vulnerability tests to identify a range of encryption vulnerabilities.

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Greenbone AG

Vulnerability management in 12 minutes

Why is Greenbone not a security provider like any other? How did Greenbone come about and what impact does Greenbone’s long history have on the quality of its vulnerability scanners and the security of its customers? The new video “Demystify Greenbone” provides answers to these questions in an twelve-minute overview. It shows why experts need their own specialised vocabulary for detecting vulnerabilities and what it means.

Greenbone is a technology-focussed company that promotes the open source idea to achieve maximum security for companies and institutions. In the video you will learn how Greenbone uses open source code to create a customised portfolio and which solutions are best suited to optimally secure your network. How do the feeds affect the solutions? What deployment models does Greenbone offer? Discover it. Discover Greenbone. Demystify Greenbone!

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Markus Feilner

“Security crises are like earthquakes” – Greenbone CEO Jan-Oliver Wagner at the PITS Congress 2024

“Support for early crisis detection” was the topic of a high-profile panel on the second day of this year’s PITS Congress. On stage: Greenbone CEO Jan-Oliver Wagner together with other experts from the Federal Criminal Police Office, the German Armed Forces, the Association of Municipal IT Service Providers VITAKO and the Federal Office for Information Security.

On security crises f.l.t.r.: Dr. Jan-Oliver Wagner, CEO (Greenbone), Dr. Dirk Häger, Head of Operational Cyber Security Department (Federal Office for Information Security), Katrin Giebel, Head of Office (VITAKO Federal Association of Municipal IT Service Providers), Major General Dr. Michael Färber, Head of Planning and Digitization Department (Cyber & Information Command) and Carsten Meywirth, Head of Cybercrime Department (Federal Criminal Police Office).

Once again this year, Behörden Spiegel organized its popular conference on Public IT Security (PITS). Hundreds of security experts gathered at the renowned Hotel Adlon in Berlin for two days of forums, presentations and an exhibition of IT security companies. In 2024, the motto of the event was “Security Performance Management” – and so it was only natural that Greenbone, as a leading provider of vulnerability management, was also invited (as in 2023), for example in the panel on early crisis detection, which Greenbone CEO Dr. Jan-Oliver Wagner opened with a keynote speech.

In his presentation, Jan-Oliver Wagner explained his view on strategic crisis detection, talking about the typical “earthquakes” and the two most important components: Knowing where vulnerabilities are, and providing technologies to address them.

Greenbone has built up this expertise over many years, also making it vailable to the public, in open source, always working together with important players on the market. For example, contacts with the German Federal Office for Information Security (BSI) were there right from the start: “The BSI already had the topic of vulnerability management on its radar when IT security was still limited to firewalls and antiviruses,” Wagner is praising the BSI, the German government’s central authority for IT security.

Today, the importance of two factors is clear: “Every organization must know how and where it is vulnerable, know its own response capabilities and has to keep working on improving them continuously. Cyber threats are like earthquakes. We can’t prevent them, we can only prepare for them and respond to them in the best possible way.”

“A crisis has often happened long before the news break”

According to Jan-Oliver Wagner’s definition, the constant cyber threat evolves into a veritable “crisis” when, for example, a threat “hits a society, economy or nation where many organizations have a lot of vulnerabilities and a low ability to react quickly. Speed is very important. You have to be faster than the attack happens.” The other participants on the panel also addressed this and used the term “getting ahead of the wave”.

The crisis is often already there long before it is mentioned in the news, individual organizations need to protect themselves and prepare themselves so that they can react to unknown situations on a daily basis. “A cyber nation supports organizations and the nation by providing the means to achieve this state,” says Jan-Oliver Wagner.

Differences between the military and local authorities

Major General Dr Michael Färber, Head of Planning and Digitalization, Cyber & Information Space Command, explained the Bundeswehr’s perspective: According to him, a crisis occurs when the measures and options for responding are no longer sufficient. “Then something develops into a crisis.”

From the perspective of small cities and similar local authorities, however, the picture is different, according to Katrin Giebel, Head of VITAKO, the Federal Association of Municipal IT Service Providers. “80 percent of administrative services take place at the municipal level. Riots would already occur when the vehicle registration is not available.” Cities and municipalities keep being hit hard by cyber attacks, and crises start much earlier here: “For us, threats are almost the same as a crisis.”

Massive negligence in organizations is frightening, says BSI

The BSI, on the other hand, defines a “crisis” as when an individual organization is unable or no longer able to solve a problem on its own. Dr Dirk Häger, Head of the Operational Cyber Security Department at the BSI: “As soon as two departments are affected, the crisis team convenes. For us, a crisis exists as soon as we cannot solve a problem with the standard organization.” This is giving a crucial role to those employees who decide whether to call together a meeting or not. “You just reach a point where you agree: now we need the crisis team.”

Something that Häger finds very frightening, however, is how long successful attacks continue to take place after crises have actually already been resolved, for example in view of the events surrounding the Log4j vulnerability. “We put a lot of effort into this, especially at the beginning. The Log4j crisis was over, but many organizations were still vulnerable and had inadequate response capabilities. But nobody investigates it anymore,” complains the head of department from the BSI.

How to increase the speed of response?

Asked by moderator Dr. Eva-Charlotte Proll, editor-in-chief and publisher at Behörden Spiegel, what would help in view of these insights, he describes the typical procedure and decision-making process in the current, exemplary checkpoint incident: “Whether something is a crisis or not is expert knowledge. In this case, it was a flaw that was initiated and exploited by state actors.” Action was needed at the latest when the checkpoint backdoor was beginning to be exploited by other (non-state) attackers. Knowledge of this specific threat situation is also of key importance for those affected.

Also Jan Oliver Wagner once again emphasized the importance of the knowledge factor. Often the threat situation is not being discussed appropriately. At the beginning of 2024, for example, an important US authority (NIST) reduced the amount of information in its vulnerability database – a critical situation for every vulnerability management provider and their customers. Furthermore, the fact that NIST is still not defined as a critical infrastructure shows that action is needed.

The information provided by NIST is central to the National Cyber Defense Center’s ability to create a situational picture as well, agrees Färber. This also applies to cooperation with the industry: several large companies “boast that they can deliver exploit lists to their customers within five minutes. We can improve on that, too.”

Carsten Meywirth, Head of Department at the BKA, emphasized the differences between state and criminal attacks, also using the example of the supply chain attack on Solarwinds. Criminal attackers often have little interest in causing a crisis because too much media attention might jeopardize their potential financial returns. And security authorities need to stay ahead of the wave – which requires intelligence and the potential to disrupt the attackers’ infrastructure.

BKA: International cooperation

According to Major General Färber, Germany is always among the top 4 countries in terms of attacks. The USA is always in first place, but states like Germany end up in the attackers’ dragnets so massively simply because of their economy’s size. This is what makes outstanding international cooperation in investigating and hunting down perpetrators so important. “Especially the cooperation of Germany, the USA and the Netherlands is indeed very successful, but the data sprints with the Five Eyes countries (USA, UK, Australia, Canada and New Zealand) are also of fundamental importance, because that is where intelligence findings come to the table, are being shared and compared. “Successful identification of perpetrators is usually impossible without such alliances,” says Michael Färber. But Germany is well positioned with its relevant organizations: “We have significantly greater redundancy than others, and that is a major asset in this fight.” In the exemplary “Operation Endgame“, a cooperation between the security authorities and the private sector launched by the FBI, the full power of these structures is now becoming apparent. “We must and will continue to expand this.”

“We need an emergency number for local authorities in IT crises”

Getting ahead of the situation like this is still a dream of the future for the municipalities. They are heavily reliant on inter-federal support and a culture of cooperation in general. An up-to-date picture of the situation is “absolutely important” for them, Katrin Giebel from VITAKO reports. As a representative of the municipal IT service providers, she is very familiar with many critical situations and the needs of the municipalities – from staff shortages to a lack of expertise or an emergency number for IT crises that is still missing today. Such a hotline would not only be helpful, but it would also correspond to the definition from Wagner’s introductory presentation: “A cyber nation protects itself by helping companies to protect themselves.”

BSI: prevention is the most important thing

Even if the BSI does not see itself in a position to fulfil such a requirement on its own, this decentralized way of thinking has always been internalized. But whether the BSI should be developed into a central office in this sense is something that needs to be discussed first, explains Dirk Häger from the BSI. “But prevention is much more important. Anyone who puts an unsecured system online today will quickly be hacked. The threat is there. We must be able to fend it off. And that is exactly what prevention is.”

Wagner adds that information is key to this. And distributing information is definitely a task for the state, which is where he sees the existing organizations in the perfect role.

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Markus Feilner

Protection of Office Suites: Greenbone Integrates Additional BSI Basic and CIS Guidelines

The IT-Grundschutz-Compendium of the Federal Office for Information Security (BSI) has, in recent years, provided clear guidelines for users of Microsoft Office. Since April 2024, Greenbone’s enterprise products have integrated tests to verify whether a company is implementing these instructions. The BSI guidelines are aligned with the Center for Internet Security (CIS) guidelines.

In the section “APP:Applications 1.1. Office Products” the BSI specifies the “requirements for the functionality of Office product components.” The goal is to protect the data processed and used by the Office software. While Microsoft Office is likely the primary reference due to its widespread market penetration, the model behind the BSI guidelines aims to apply to any office product “that is locally installed and used to view, edit, or create documents, excluding email applications.”

BSI Guidelines

The module explicitly builds on the requirements of the “APP.6 General Software” component and refers to the modules “APP.5.3 General Email Client,” “APP.4.3 Relational Databases,” and “OPS.2.2 Cloud Usage,” although it expressly does not consider these.

The BSI identifies three main threats to Office suites:

  • Lack of customization of Office products to the institution’s needs
  • Malicious content in Office documents
  • Loss of integrity of Office documents

The components listed in the BSI IT-Grundschutz-Compendium include 16 points, some of which have since been removed. Greenbone has developed several hundred tests, primarily addressing five of the basic requirements, including “Secure opening of documents from external sources” (APP.1.1. A3) and “Use of encryption and digital signatures” listed in APP.1.1. A15. The BSI specifies:

“All documents obtained from external sources MUST be checked for malware before being opened. All file formats deemed problematic and all unnecessary within the institution MUST be banned. If possible, they SHOULD be blocked. Technical measures SHOULD enforce that documents from external sources are checked.”

Regarding encryption, it states: “Data with increased protection requirements SHOULD only be stored or transmitted in encrypted form. Before using an encryption method integrated into an Office product, it SHOULD be checked whether it offers sufficient protection. Additionally, a method SHOULD be used that allows macros and documents to be digitally signed.”

CIS Guidelines Enhance Basic Protection

In addition to the requirements listed in the BSI Basic Protection Manual, the CIS Benchmark from the Center for Internet Security (CIS) for Microsoft Office includes further and more specific suggestions for securing Microsoft products. The CIS guidelines are developed by a community of security experts and represent a consensus-based best practice collection for Microsoft Office.

As one of the first and only vulnerability management providers, Greenbone now offers tests on security-relevant features mentioned in the CIS guidelines, uniting CIS and BSI instructions in numerous, sometimes in-depth tests, such as on ActiveX Control Initialization in Microsoft Office. The Greenbone Vulnerability Management tests whether this switch is set to “enabled”, but also many other settings, for example, whether “Always prevent untrusted Microsoft Query files from opening” is set to “Enabled” among many others.

Many tests focus on external content, integrating macros, and whether and how these external contents are signed, verifiable, and thus trustworthy or not, and whether administrators have done their homework in configuring Microsoft Office. According to the BSI, one of the most significant threats (and the first mentioned) is the lack of adaptation of Office products to the reality and the business processes in the company. Greenbone’s new tests ensure efficient compliance with regulations, making it harder for attackers and malware to establish a foothold and cause damage in the company.

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Greenbone AG

PITS 2024 Public IT Security

Save the date: The “German Congress for IT and Cyber Security in Government and Administration” (June 12 to 13, 2024) provides information on current trends, strategies and solutions in IT security.

In the main program: “IT support for early crisis detection” (Moderation: Dr. Eva-Charlotte Proll, Editor-in-Chief and Publisher, Behörden Spiegel).

Participants:

  • Dr. Jan-Oliver Wagner, Chief Executive Officer Greenbone
  • Carsten Meywirth, Head of the Cybercrime Division, Federal Criminal Police Office
  • Generalmajor Dr. Michael Färber, Head of Planning and Digitization, Cyber & Information Space Command
  • Katrin Giebel, Branch Manager, VITAKO Bundesverband kommunaler IT-Dienstleister e.V.
  • Dr. Dirk Häger, Head of the Operational Cybersecurity Department, Federal Office for Information Security (BSI)

Where? Berlin, Hotel Adlon Kempinski, Unter den Linden 77
When? 13.06.2024; 9:40 a.m.

Vulnerabilities in IT systems are increasingly being exploited by malicious attackers. You can protect your IT systems with vulnerability management. Visit us in our lounge at stand 44 – we look forward to seeing you!

Registration: https://www.public-it-security.de/anmeldung/

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Greenbone AG

The new SMP federal portal in partnership with the Federal Office for Information Security (BSI)

We at Greenbone are excited to introduce the innovative Greenbone SMP-Bund-Portal in collaboration with the Federal Office for Information Security (BSI). As a leading provider of IT security solutions, we are proud to offer this platform specifically tailored to the needs of federal agencies.

A Portal Setting Standards

The Greenbone SMP-Bund-Portal is the central point of contact for IT security and vulnerability management. It has been developed to provide agencies with concrete support in addressing current IT security challenges.

Many Advantages for Federal Agencies

  1. Easy-to-Understand Insights: The portal offers clear and user-friendly information about vulnerability management. It is ideal for both beginners and experts in IT security.
  2. Exclusive Framework Contract Conditions: Federal agencies enjoy special offers and benefits. The obligation to issue public tenders is eliminated, saving time and resources.
  3. Personal Support: Our competent support team is always at our customers’ side to answer questions and ensure support.
  4. Direct Access to the Agency Sales Team: Expert advice from our team, which is well-versed in the specific requirements of federal agencies. We look forward to furthering our trusted collaboration with the BSI and are available for any questions.
  5. Opportunity for Exchange: Use the shared forum to share your experiences and questions.

https://smp-bund.greenbone.net/

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Greenbone AG

The Confluence of Open Source and Cybersecurity in companies: Insights from Greenbone at #OSXP2023 in Paris

International panel discussion on effective cybersecurity at #OSXP2023

At the esteemed #OSXP2023 event, that took place in Paris, our participation in the “Cybersécurité et open source” roundtable brought forward critical discussions on improving cybersecurity in companies. The panel, including distinguished experts from the academic and governmental sectors, delved into strategies and points of vigilance essential for robust cybersecurity.

1. The Mindset of Security

Security by Design: A Leadership Commitment

  • The panel emphasized the importance of incorporating security from the initial stages of development. This approach requires a commitment from the top management to prioritize security in all business operations.

A Mentality Focused on Secure and Protected Solutions

  • Companies must cultivate a culture where security is an integral part of the thinking process, aiming to deliver solutions that are inherently secure and protected.

2. Implementing Key Processes

Adherence to Standards and Automation

  • The importance of adhering to established cybersecurity standards was underscored, with a recommendation to automate processes wherever possible to ensure consistency and efficiency.

No Deployment Without Security Compliance

  • It was strongly advised that no deployments or actions should proceed without meeting the necessary security requirements.

3. Resources: Empowering Teams and Enhancing Vigilance

Dedicated Security Teams and Training

  • Having specialized security teams and conducting regular training sessions were identified as crucial for maintaining a high level of security awareness and preparedness.

Vigilance as a Continuous Effort

  • Continuous vigilance was highlighted as a key resource, ensuring that security measures are always up-to-date and effective.

4. Essential Tools and Technologies

Mandatory Multi-Factor Authentication (MFA)

  • Implementing MFA as a compulsory measure we recommend enhancing account security significantly.

Vulnerability Scanners and Dependance Management

  • Utilizing vulnerability scanners and managing dependencies and configurations were suggested as vital tools. While platforms like GitHub Enterprise may be costly, they offer comprehensive solutions for these needs.

Conclusion: Education, Awareness, and the Use of Open-Source Tools

In conclusion, the panel at #OSXP2023, including our expert Corentin Bardin, a cyber security specialist and pen tester, highlighted the importance of continuous education and staying updated in the rapidly evolving cybersecurity landscape. They advocated for the use of open-source tools to bolster security measures.

The key takeaway from the discussion is the commitment to offering secure services. It’s not just about the tools and processes; it’s about the mindset and ongoing effort to stay vigilant and informed.


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Elmar Geese

Supposedly pro-Russian hackers try to exploit Sharepoint vulnerability

Update from 2023-12-06:

Last week, we reported on pro-Russian hacktivists scanning for vulnerable SharePoint Servers to exploit a critical vulnerability (CVE-2023-29357).

New findings suggest that the group, calling themselves “Zarya”, is undertaking various exploit-attempts, including directory traversal and targeting specific vulnerabilities in systems such as OpenWRT-Routers. The IP address 212.113.106.100, associated with these activities, has been observed in several different exploit attempts. In addition to simple reconnaissance, specific attacks on configuration files and Admin-APIs have been detected. This case re-emphasizes the importance of securing systems against such threats and shows, how unprotected or poorly configured systems can become targets of such attacks.

A critical vulnerability for Sharepoint (CVE-2023-29357), is being targeted by presumably pro-Russian attackers who are trying to exploit this vulnerability.

The Internet Storm Center has discovered corresponding activity on its honeypots. The severity for this vulnerability is critical (a score of 9.8 out of 10), and the attack complexity is very low, making this vulnerability particularly dangerous. Greenbone customers can benefit from the automatic detection of this vulnerability in our Enterprise Feed. Microsoft offers a security update since June 12, 2023, Microsoft customers who missed the update should install it now.


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Greenbone AG

IT security update November 2023: Critical vulnerabilities and threats

In the November 2023 commVT Intelligence Update, several critical vulnerabilities and security threats have come to light. Cisco’s Internetworking Operating System (IOS) XE Software Web User Interface (UI) was found to be vulnerable to two actively exploited critical vulnerabilities, allowing attackers to execute arbitrary code remotely. The curl command-line tool, widely used across various platforms, faced a serious vulnerability that could result in arbitrary code execution during SOCKS5 proxy handshakes. VMware is urging immediate updates for its vCenter Server due to a critical vulnerability potentially leading to remote code execution. Multiple vulnerabilities were found in versions of PHP 8; one is a particularly critical deserialization vulnerability in the PHAR extraction process. Additionally, SolarWinds Access Rights Manager (ARM) was found susceptible to multiple critical vulnerabilities, emphasizing the urgency to update to version 2023.2.1. Lastly, two F5 BIG-IP vulnerabilities were discovered to be actively exploited, with mitigation options available and outlined below.

Cisco IOS XE: Multiple Critical Vulnerabilities

Two actively exploited critical CVSS 10 vulnerabilities were discovered in Cisco’s Internetworking Operating System (IOS) XE Software Web User Interface (UI); CVE-2023-20198 and CVE-2023-20273. Combined, they allow an attacker to remotely execute arbitrary code as the system user and are estimated to have been used to exploit tens of thousands of vulnerable devices within the past few weeks. Greenbone has added detection for both the vulnerable product by version [1], and another aimed at detecting the BadCandy implanted configuration file [2]. Both are VTs included in Greenbone’s Enterprise vulnerability feed.

Cisco IOS was created in the 1980s and used as the embedded OS in the networking technology giant’s routers. Fast forward to 2023, IOS XE is a leading enterprise networking full-stack software solution that powers Cisco platforms for access, distribution, core, wireless, and WAN. IOS XE is Linux-based, and specially optimized for networking and IT infrastructure, routing, switching, network security, and management. Cisco devices are pervasive in global IT infrastructure and used by organizations of all sizes, including large-scale enterprises, government agencies, critical infrastructure, and educational institutions.

Here’s how the two recently disclosed CVEs work:

• CVE-2023-20198 (CVSS 10 Critical): Allows a remote, unauthenticated attacker to create an account [T1136] on an affected system with privilege level 15 (aka privileged EXEC level) access [CWE-269]. Privilege level 15 is the highest level of access to Cisco IOS. The attacker can then use that account to gain control of the affected system.
• CVE-2023-20273 (CVSS 7.2 High): A regular user logged into the IOS XE web UI, can inject commands [CWE-77] that are subsequently executed on the underlying system with the system (root) privileges. This vulnerability is caused by insufficient input validation [CWE-20]. CVE is also associated with a Lua-based web-shell [T1505.003] implant dubbed “BadCandy”. BadCandy consists of an Nginx configuration file named `cisco_service.conf` that establishes a URI path to interact with the web-shell implant but requires the webserver to be restarted.

Cisco has released software updates for mitigating both CVEs in IOS XE software releases, including versions 17.9, 17.6, 17.3, and 16.12 as well as available Software Maintenance Upgrades (SMUs) and IT security teams are strongly advised to urgently install them. Cisco has also released associated indicators of compromise (IoC), Snort rules for detecting active attacks, and a TAC Technical FAQs page. Disabling the web UI prevents exploitation of these vulnerabilities and may be suitable mitigation until affected devices can be upgraded. Publicly released proof of concept (PoC) code [1][2] and a Metasploit module further increase the urgency to apply the available security updates.

Critical Vulnerability In The Curl Tool

A widespread vulnerability has been discovered in the popular curl command line tool, libcurl, and the many software applications that leverage them across a wide number of platforms. Tracked as CVE-2023-38545 (CVSS 9.8 Critical), the flaw makes curl overflow a heap-based buffer [CWE-122]] in the SOCKS5 proxy handshake that can result in arbitrary code execution [T1203]. Greenbone’s community feed includes several NVTs [1] to detect many of the affected software products and will add additional detections for CVE-2023-38545 as more vulnerable products are identified.

CVE-2023-38545 is a client-side vulnerability exploitable when passing a hostname to the SOCKS5 proxy that exceeds the maximum length of 255 bytes. If supplied with an excessively long hostname, curl is supposed to use local name resolution and pass it on to the resolved address only. However, due to the CVE-2023-38545 flaw, curl may actually copy the overly long hostname to the target buffer instead of copying just the resolved address there. The target buffer, being a heap-based buffer, and the hostname coming from the URL results in the heap-based overflow.

While the severity of the vulnerability is considered high because it can be exploited remotely and has a high impact to the confidentiality, integrity, and availability (CIA) of the underlying system, the SOCKS5 proxy method is not the default connection mode and must be declared explicitly. Additionally, for an overflow to happen an attacker also needs to cause a slow enough SOCKS5 handshake to trigger the bug. All versions of curl are affected between v7.69.0 (released March 4th, 2020) until v8.3.0. The vulnerable code was patched in v8.4.0 commit 4a4b63daaa.

VMware vCenter Server: Multiple Vulnerabilities

CVE-2023-34048 is a critical severity vulnerability that could allow a malicious actor with network access to vCenter Server to cause an out-of-bounds write [CWE-787] potentially leading to remote code execution (RCE). The affected software includes VMware vCenter Server versions 6.5, 6.7, 7.0, and 8.0. VMWare has issued a security advisory to address both vulnerabilities which states that there are no known mitigations other than installing the provided updates. Both vulnerabilities can be detected by Greenbone’s enterprise vulnerability feed [1]. The vCenter Server patch also fixes CVE-2023-34056, a medium-severity information disclosure resulting from improper authorization [CWE-285].

Although there are no reports that CVE-2023-34048 is being actively exploited in the wild attackers have proven adept at swiftly converting threat intelligence into exploit code. Research by Palo Alto Networks Unit 42 threat research group shows that on average an exploit is published 37 days after a security patch is released.

Here are some brief details on both CVEs:

• CVE-2023-34048 (CVSS 9.8 Critical): vCenter Server contains an out-of-bounds write [CWE-787] vulnerability in the implementation of the DCERPC protocol. A malicious actor with network access to vCenter Server may trigger this vulnerability to achieve remote code execution (RCE). The Distributed Computing Environment Remote Procedure Call (DCERPC) protocol facilitates remote procedure calls (RPC) in distributed computing environments, allowing applications to communicate and invoke functions across networked systems.
• CVE-2023-34056 (CVSS 4.3 Medium): vCenter Server contains a partial information disclosure vulnerability. A malicious actor with non-administrative privileges to vCenter Server may leverage this issue to access unauthorized data.

Multiple Vulnerabilities Discovered In PHP 8

Several vulnerabilities were identified in PHP 8.0.X before 8.0.28, 8.1.X before 8.1.16 and 8.2.X before 8.2.3. Although the group of vulnerabilities does include one critical and two high-severity vulnerabilities, these require particular contexts to be present for exploitation; either deserializing PHP applications using PHAR or else using PHP’s core path resolution functions on untrusted input. Greenbone’s enterprise VT feed includes multiple detection tests for these vulnerabilities across multiple platforms.

Here are brief descriptions of the most severe recent PHP 8 vulnerabilities:

• CVE-2023-3824 (CVSS 9.8 Critical): A PHAR file (short for PHP Archive) is a compressed packaging format in PHP, which is used to distribute and deploy complete PHP applications in a single archive file. While reading directory entries during the PHAR archive loading process, insufficient length checking may lead to a stack buffer overflow [CWE-121], potentially leading to memory corruption or remote code execution (RCE).
• CVE-2023-0568 (CVSS 8.1 High): PHP’s core path resolution function allocates a buffer one byte too small. When resolving paths with lengths close to the system `MAXPATHLEN` setting, this may lead to the byte after the allocated buffer being overwritten with NULL value, which might lead to unauthorized data access or modification. PHP’s core path resolution is used for the `realpath()` and `dirname()` functions, when including other files using the `include()`, `include_once()`, `require()`, and `require_once()`, and during the process of resolving PHP’s “magic” constants” such as `__FILE__` and `__DIR__`.
• CVE-2023-0567 (CVSS 6.2 Medium): PHP’s `password_verify()` function may accept some invalid Blowfish hashes as valid. If such an invalid hash ever ends up in the password database, it may lead to an application allowing any password for this entry as valid [CWE-287]. Notably, this vulnerability has been assigned different CVSS scores by NIST (CVSS 6.2 Medium) and the PHP group CNA (CVSS 7.7 High), the difference being that the PHP Group CNA considers CVE-2023-0567 a high risk to confidentiality while NIST does not. CNAs are a group of independent vendors, researchers, open source software developers, CERT, hosted service, and bug bounty organizations authorized by the CVE Program to assign CVE IDs and publish CVE records within their own specific scopes of coverage.

SolarWinds Access Rights Manager (ARM): Multiple Critical Vulnerabilities

SolarWinds Access Rights Manager (ARM) prior to version 2023.2.1 is vulnerable to 8 different exploits; one critical and two additional high-severity vulnerabilities (CVE-2023-35182, CVE-2023-35185, and CVE-2023-35187). These include authenticated and unauthenticated privilege escalation [CWE-269], directory traversal [CWE-22], and remote code execution (RCE) at the most privileged “SYSTEM” level. Greebone’s Enterprise vulnerability feed includes both local security check (LSC) [1] and remote HTTP detection [2].

SolarWinds ARM is an enterprise access control software for Windows Active Directory (AD) networks and other resources such as Windows File Servers, Microsoft Exchange services, and Microsoft SharePoint as well as virtualization environments, cloud services, NAS devices, and more. The widespread use of ARM and other SolarWinds software products means that its vulnerabilities have a high potential to impact a wide range of large organizations including critical infrastructure.

These and more recent vulnerabilities are disclosed in SolarWinds’ security advisories. Although no reports of active exploitation have been released, mitigation is highly recommended and available by installing SolarWinds ARM version 2023.2.1.

F5 BIG-IP: Unauthenticated RCE And Authenticated SQL Injection Vulnerabilities

Two RCE vulnerabilities in F5 BIG-IP, CVE-2023-46747 (CVSS 9.8 Critical) and CVE-2023-46748 (CVSS 8.8 High), have been observed by CISA to be actively exploited in the wild soon after PoC code was released for CVE-2023-46747. A Metasploit exploit module has also since been published. F5 BIG-IP is a family of hardware and software IT security products for ensuring that applications are always secure and perform the way they should. The platform is produced by F5 Networks, and it focuses on application services ranging from access and delivery to security. Greenbone has added detection for both CVEs [1][2].

CVE-2023-46747 is a remote authentication bypass [CWE-288] vulnerability while CVE-2023-46748 is a remote SQL injection vulnerability [CWE-89] that can only be exploited by an authenticated user. The affected products include the second minor release (X.1) for major versions 14-17 of BIG-IP Advanced Firewall Manager (AFM) and F5 Networks BIG-IP Application Security Manager (ASM).

If you are running an affected version you can eliminate this vulnerability by installing the vendor-provided HOTFIX updates [1][2]. The term “hotfix” implies that the patch can be applied to a system while it is running and operational, without the need for a shutdown or reboot. If updating is not an option, CVE-2023-46747 can be mitigated by downloading and running a bash script that adds or updates the `requiredSecret` attribute in the Tomcat configuration, which is used for authentication between Apache and Tomcat, and CVE-2023-46748 can be mitigated by restricting access to the Configuration utility to allow only trusted networks or devices, and ensuring only trusted user accounts exist thereby limiting the attack surface.


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