Tag Archives: Vulnerability

Zero-Day Remote ‘Root’ Exploit Disclosed In AT&T DirecTV WVB Devices

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Security researchers have publicly disclosed an unpatched zero-day vulnerability in the firmware of AT&T DirecTV WVB kit after trying to get the device manufacturer to patch this easy-to-exploit flaw over the past few months.

The problem is with a core component of the Genie DVR system that’s shipped free of cost with DirecTV and can be easily exploited by hackers to gain root access and take full control of the device, placing millions of people who’ve signed up to DirecTV service at risk.

The vulnerability actually resides in WVBR0-25—a Linux-powered wireless video bridge manufactured by Linksys that AT&T provides to its new customers.

DirecTV Wireless Video Bridge WVBR0-25 allows the main Genie DVR to communicate over the air with customers’ Genie client boxes (up to 8) that are plugged into their TVs around the home.

Trend Micro researcher Ricky Lawshae, who is also a DirecTV customer, decided to take a closer look at the device and found that Linksys WVBR0-25 hands out internal diagnostic information from the device’s web server, without requiring any authentication.

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When trying to browse to the wireless bridge’s web server on the device, Lawshae was expecting a login page or similar, but instead, he found “a wall of text streaming before [his] eyes.”

Once there, Lawshae was able to see the output of several diagnostic scripts containing everything about the DirecTV Wireless Video Bridge, including the WPS pin, connected clients, running processes, and much more.

What’s more worrisome was that the device was accepting his commands remotely and that too at the “root” level, meaning Lawshae could have run software, exfiltrate data, encrypt files, and do almost anything he wanted on the Linksys device.

“It literally took 30 seconds of looking at this device to find and verify an unauthenticated, remote root command injection vulnerability. It was at this point that I became pretty frustrated,” Lawshae wrote in an advisory published Wednesday on Trend Micro-owned Zero Day Initiative (ZDI) website. 

“The vendors involved here should have had some form of secure development to prevent bugs like this from shipping. More than that, we as security practitioners have failed to affect the changes needed in the industry to prevent these simple yet impactful bugs from reaching unsuspecting consumers.”

Lawshae also provided a video, demonstrating how a quick and straightforward hack let anyone get a root shell on the DirecTV wireless box in less than 30 seconds, granting them full remote unauthenticated admin control over the device.

The vulnerability was reported by the ZDI Initiative to Linksys more than six months ago, but the vendor ceased communication with the researcher and had yet not fixed the problem, leaving this easy-to-exploit vulnerability unpatched and open for hackers.

So, after over half a year, ZDI decided to publicize the zero-day vulnerability, and recommended users to limit their devices that can interact with Linksys WVBR0-25 “to those that actually need to reach” in order to protect themselves.

ROBOT Attack: 19-Year-Old Bleichenbacher Attack On Encrypted Web Reintroduced

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A 19-year-old vulnerability has been re-discovered in the RSA implementation from at least 8 different vendors—including F5, Citrix, and Cisco—that can give man-in-the-middle attackers access to encrypted messages.

Dubbed ROBOT (Return of Bleichenbacher’s Oracle Attack), the attack allows an attacker to perform RSA decryption and cryptographic operations using the private key configured on the vulnerable TLS servers.

ROBOT attack is nothing but a couple of minor variations to the old Bleichenbacher attack on the RSA encryption protocol.

First discovered in 1998 and named after Swiss cryptographer Daniel Bleichenbacher, the Bleichenbacher attack is a padding oracle attack on RSA-based PKCS#1 v1.5 encryption scheme used in SSLv2.

Leveraging an adaptive chosen-ciphertext attack which occurred due to error messages by SSL servers for errors in the PKCS #1 1.5 padding, Bleichenbacher attack allows attackers to determine whether a decrypted message is correctly padded.

This information eventually helps attackers decrypt RSA ciphertexts without recovering the server’s private key, completely breaking the confidentiality of TLS when used with RSA encryption.

“An attacker could iteratively query a server running a vulnerable TLS stack implementation to perform cryptanalytic operations that may allow decryption of previously captured TLS sessions.” Cisco explains in an advisory.

In 1998, Bleichenbacher proposed to upgrade encryption scheme, but instead, TLS designers kept the vulnerable encryption modes and added a series of complicated countermeasures to prevent the leakage of error details.

Now, a team of security researchers has discovered that these countermeasures were incomplete and just by using some slight variations, this attack can still be used against many HTTPS websites.

“We changed it to allow various different signals to distinguish between error types like timeouts, connection resets, duplicate TLS alerts,” the researchers said. 

“We also discovered that by using a shortened message flow where we send the ClientKeyExchange message without a ChangeCipherSpec and Finished message allows us to find more vulnerable hosts.”

According to the researchers, some of the most popular websites on the Internet, including Facebook and Paypal, are affected by the vulnerability. The researchers found “vulnerable subdomains on 27 of the top 100 domains as ranked by Alexa.

ROBOT attack stems from the above-mentioned implementation flaw that only affects TLS cipher modes using RSA encryption, allowing an attacker to passively record traffic and later decrypt it.

“For hosts that usually use forward secrecy, but still support a vulnerable RSA encryption key exchange the risk depends on how fast an attacker is able to perform the attack,” the researchers said. 

“We believe that a server impersonation or man in the middle attack is possible, but it is more challenging.”

The ROBOT attack has been discovered by Hanno Böck, Juraj Somorovsky of Ruhr-Universitat Bochum/Hackmanit GmbH, and Craig Young of Tripwire VERT, who also created a dedicated website explaining the whole attack, its implications, mitigations and more.

The attack affects implementations from several different vendors, some of which have already released patches and most have support notes acknowledging the issue.

You will find the list of affected vendors on the ROBOT website.

The researchers have also released a python tool to scan for vulnerable hosts. You can also check your HTTPS server against ROBOT attack on their website.

Android Flaw Lets Hackers Inject Malware Into Apps Without Altering Signatures

Android Flaw Lets Hackers Inject Malware Into Apps Without Altering Signatures

Millions of Android devices are at serious risk of a newly disclosed critical vulnerability that allows attackers to secretly overwrite legitimate applications installed on your smartphone with their malicious versions.

Dubbed Janus, the vulnerability allows attackers to modify the code of Android apps without affecting their signature verification certificates, eventually allowing them to distribute malicious update for the legitimate apps, which looks and works same as the original apps.

The vulnerability (CVE-2017-13156) was discovered and reported to Google by security researchers from mobile security firm GuardSquare this summer and has been patched by Google, among four dozen vulnerabilities, as part of its December Android Security Bulletin.

However, the worrisome part is that majority of Android users would not receive these patches for next few month, until their device manufacturers (OEMs) release custom updates for them, apparently leaving a large number of smartphone users vulnerable to hackers.

The vulnerability affects apps using APK signature scheme v1 installed on devices running Android versions 5 (Lollipop) and 6 (Marshmallow).

Explained: How Android Janus Vulnerability Works?

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The vulnerability resides in the way Android handles APK installation for some apps, leaving a possibility to add extra bytes of code to an APK file without affecting the application’s signature.

Before proceeding further, you need to know some basics about an APK file.

A valid APK file is a type of archive file, just like Zip, which includes application code, resources, assets, signatures, certificates, and manifest file.

Earlier versions of Android operating system 5.0 (Lollipop) and 6.0 (Marshmallow) also support a process virtual machine that helps to execute APK archives containing a compiled version of application code and files, compressed with DEX (Dalvik EXecutable) file format.

While installing an Android app or its update, your device checks APK header information to determine if the archive contains code in the compressed DEX files.

If header says APK archive contains DEX files, the process virtual machine decompiles the code accordingly and executes it; otherwise, it runs the code as a regular APK file.

It turns out that an APK archive can contain DEX files as well as regular application code simultaneously, without affecting its validity and signatures.

Researchers find that this ability to add extra bytes of code due to lack of file integrity checking could allow attackers to prepend malicious code compiled in DEX format into an APK archive containing legitimate code with valid signatures, eventually tricking app installation process to execute both code on the targeted device without being detected.

In other words, the hack doesn’t require attackers to modify the code of legitimate applications (that makes signatures invalid)—instead, the vulnerability allows malware authors to merely add some extra malicious lines of code to the original app.

Attack Scenarios

After creating malicious but valid versions of legitimate applications, hackers can distribute them using various attack vectors, including spam emails, third-party app stores delivering fake apps and updates, social engineering, and even man-in-the-middle attacks.

According to the researchers, it may be “relatively easy to trick some users because the application can still look exactly like the original application and has the proper signature.”

I find man-in-the-middle attack more interesting, as it could allow hackers to push malicious installation for the apps designed to receive its updates over an unencrypted HTTP connection.

“When the user downloads an update of an application, the Android runtime compares its signature with the signature of the original version. If the signatures match, the Android runtime proceeds to install the update,” GuardSquare explains. 

“The updated application inherits the permissions of the original application. Attackers can, therefore, use the Janus vulnerability to mislead the update process and get an unverified code with powerful permissions installed on the devices of unsuspecting users.” 

“For experts, the common reverse engineering tools do not show the injected code. Users should always be vigilant when downloading applications and updates,” the security firm added.

Since this vulnerability does not affect Android 7 (Nougat) and latest, which supports APK signature scheme version 2, users running older Android versions are highly recommended to upgrade their device OS (if available).

It’s unfortunate, but if your device manufacturer neither offers security patches nor the latest Android version, then you should not install apps and updates from outside of Google Play Store to minimise the risk of being hacked.

Researchers also advised Android developers always to apply signature scheme v2 in order to ensure their apps cannot be tampered with.

Critical Flaw in Major Android Tools Targets Developers and Reverse Engineers

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Finally, here we have a vulnerability that targets Android developers and reverse engineers, instead of app users.

Security researchers have discovered an easily-exploitable vulnerability in Android application developer tools, both downloadable and cloud-based, that could allow attackers to steal files and execute malicious code on vulnerable systems remotely.

The issue was discovered by security researchers at the Check Point Research Team, who also released a proof of concept (PoC) attack, which they called ParseDroid.

The vulnerability resides in a popular XML parsing library “DocumentBuilderFactory,” used by the most common Android Integrated Development Environments (IDEs) like Google’s Android Studio, JetBrains’ IntelliJ IDEA and Eclipse as well as the major reverse engineering tools for Android apps such as APKTool, Cuckoo-Droid and more.

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The ParseDroid flaw, technically known as XML External Entity (XXE) vulnerability, is triggered when a vulnerable Android development or reverse engineering tool decodes an application and tries to parse maliciously crafted “AndroidManifest.xml” file inside it.

In order words, all an attacker need to trigger the vulnerability is trick the developers and reverse engineers into loading a maliciously crafted APK file.

“By simply loading the malicious ‘AndroidManifest.xml’ file as part of an Android project, the IDEs starts spitting out any file configured by the attacker,” the researchers said.

Demonstration: XML External Entity (XXE) to Remote Code Execution

Besides this, the XXE vulnerability can also be used to inject arbitrary files anywhere on a targeted computer to achieve full remote code execution (RCE), which makes the attack surface-wide and various.

Moreover, the attacker doesn’t require to target their victims directly, as the researchers suggest “another attack scenario that can be used in the wild to attack a massive range of Android developers by injecting a malicious AAR (Android Archive Library) containing our XXE payload into repositories.”

For educational and demonstration purpose, researchers have also created an online APK decoder tool that can extract the malicious file from an APK (in this case they used a PHP web shell), allowing the attacker to execute system commands on the web application server, as shown in the video.

“The way we chose to demonstrate this vulnerability, of course, is just one of many possible attack methods that can be used to achieve full RCE,” the Check Point researchers wrote. “Indeed, the Path Traversal method lets us copy any file to any location on the file system, making the attack surface-wide and various.”

Check Point researchers Eran Vaknin, Gal Elbaz, Alon Boxiner and Oded Vanunu discovered this issue in May 2017 and reported them to all major IDEs and tools developers, including Google, JetBrains, Eclipse and APKTool owner.

Most of the developers, including Google, JetBrains and APKTool owner, have since fixed the issue and released patched versions.

Since all the attack methods demonstrated by the researchers are cross-platform, developers and reverse engineers are highly recommended to update their tools, if they haven’t yet.

Hackers Exploit Recently Disclosed Microsoft Office Bug to Backdoor PCs

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A recently disclosed severe 17-year-old vulnerability in Microsoft Office that lets hackers install malware on targeted computers without user interaction is now being exploited in the wild to distribute a backdoor malware.

First spotted by researchers at security firm Fortinet, the malware has been dubbed Cobalt because it uses a component from a powerful and legitimate penetration testing tool, called Cobalt Strike.

Cobalt Strike is a form of software developed for Red Team Operations and Adversary Simulations for accessing covert channels of a system.

The vulnerability (CVE-2017-11882) that Cobalt malware utilizes to deliver the backdoor is a memory-corruption issue that allows unauthenticated, remote attackers to execute malicious code on the targeted system when opened a malicious file and potentially take full control over it.

This vulnerability impacts all versions of Microsoft Office and Windows operating system, though Microsoft has already released a patch update to address the issue. You can read more details and impact of the vulnerability in our previous article.

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Since cybercriminals are quite quick in taking advantage of newly disclosed vulnerabilities, the threat actors started delivering Cobalt malware using the CVE-2017-11882 exploit via spam just a few days after its disclosure.

According to Fortinet researchers, the Cobalt malware is delivered through spam emails, which disguised as a notification from Visa regarding rule changes in Russia, with an attachment that includes a malicious RTF document, as shown.

The email also contains a password-protected archive with login credentials provided in the email to unlock it in order to trick victims into believing that the email came from the legitimate financial service.

“This is [also] to prevent auto-analysis systems from extracting the malicious files for sandboxing and detection,” Fortinet researchers Jasper Manual and Joie Salvio wrote.

“Since a copy of the malicious document is out in the open… so it’s possible that this is only to trick the user into thinking that securities are in place, which is something one would expect in an email from a widely used financial service.”

Once the document is opened, the user has displayed a plain document with the words “Enable Editing.” However, a PowerShell script silently executes in the background, which eventually downloads a Cobalt Strike client to take control of the victim’s machine.

With control of the victim’s system, hackers can “initiate lateral movement procedures in the network by executing a wide array of commands,” the researchers said.

According to the researchers, cybercriminals are always in look for such vulnerabilities to exploit them for their malware campaigns, and due to ignoring software updates, a significant number of users out there left their systems unpatched, making them vulnerable to such attacks.

The best way to protect your computer against the Cobalt malware attack is to download the patch for the CVE-2017-11882 vulnerability and update your systems immediately.

Remotely Exploitable Flaw Found In HP Enterprise Printers—Patch Now

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Security researchers have discovered a potentially dangerous vulnerability in the firmware of various Hewlett Packard (HP) enterprise printer models that could be abused by attackers to run arbitrary code on affected printer models remotely.

The vulnerability (CVE-2017-2750), rated as high in severity with 8.1 CVSS scale, is due to insufficiently validating parts of Dynamic Link Libraries (DLL) that allows for the potential execution of arbitrary code remotely on affected 54 printer models.

The security flaw affects 54 printer models ranging from HP LaserJet Enterprise, LaserJet Managed, PageWide Enterprise and OfficeJet Enterprise printers.

This remote code execution (RCE) vulnerability was discovered by researchers at FoxGlove Security when they were analyzing the security of HP’s MFP-586 printer (currently sold for $2,000) and HP LaserJet Enterprise M553 printers (sold for $500).

According to a technical write-up posted by FoxGlove on Monday, researchers were able to execute code on affected printers by reverse engineering files with the “.BDL” extension used in both HP Solutions and firmware updates.

“This (.BDL) is a proprietary binary format with no publicly available documentation,” researchers said. “We decided that reverse engineering this file format would be beneficial, as it would allow us to gain insight into exactly what firmware updates and software solutions are composed of.”

Since HP has implemented the signature validation mechanism to prevent tampering with the system, the researchers failed to upload a malicious firmware to the affected printer.

However, after some testing researchers said that “it may be possible to manipulate the numbers read into int32_2 and int32_3 in such a way that the portion of the DLL file having its signature verified could be separated from the actual executable code that would run on the printer.”

The researchers were able to bypass digital signature validation mechanism for HP software “Solution” package and managed to add a malicious DLL payload and execute arbitrary code.

FoxGlove Security has made the source code of the tools used during its research available on GitHub, along with the proof-of-concept (PoC) malware payload that could be remotely installed on the printers.

The actions performed by their proof of concept malware are as follows:

  1. It downloads a file from http[://]nationalinsuranceprograms[.]com/blar
  2. Executes the command specified in the file on the printer
  3. Waits for 5 seconds
  4. Repeat

FoxGlove Security reported this remote code execution vulnerability to HP in August this year, and the vendor fixed the issue with the release of new firmware updates for its business and enterprise printers.

To download the new firmware update, visit the HP website in your web browser, and select Support from the top of the page and select Software & drivers. Now, enter the product name or model number in the search box, then scroll down in the search results to firmware and download the necessary files.

Highly Critical Flaw (CVSS Score 10) Lets Hackers Hijack Oracle Identity Manager

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A highly critical vulnerability has been discovered in Oracle’s enterprise identity management system that can be easily exploited by remote, unauthenticated attackers to take full control over the affected systems.

The critical vulnerability tracked as CVE-2017-10151, has been assigned the highest CVSS score of 10 and is easy to exploit without any user interaction, Oracle said in its advisory published Monday without revealing many details about the issue.

The vulnerability affects Oracle Identity Manager (OIM) component of Oracle Fusion Middleware—an enterprise identity management system that automatically manages users’ access privileges within enterprises.

The security loophole is due to a “default account” that an unauthenticated attacker over the same network can access via HTTP to compromise Oracle Identity Manager.

Oracle has not released complete details of the vulnerability in an effort to prevent exploitation in the wild, but here the “default account” could be a secret account with hard-coded or no password.

“This vulnerability is remotely exploitable without authentication, i.e., may be exploited over a network without requiring user credentials,” Oracle’s advisory reads.

The easily exploitable vulnerability affects Oracle Identity Manager versions 11.1.1.7, 11.1.1.9, 11.1.2.1.0, 11.1.2.2.0, 11.1.2.3.0 and 12.2.1.3.0.

Oracle has released patches for all versions of its affected products, so you are advised to install the patches before hackers get a chance to exploit the vulnerability to target your enterprise.

“Due to the severity of this vulnerability, Oracle strongly recommends that customers apply the updates provided by this Security Alert without delay,” the company warned.

Product releases that are not under Premier Support or Extended Support are not tested for the presence of the vulnerability.

However, Oracle said it was “likely that earlier versions of affected releases are also affected by these vulnerabilities. As a result, Oracle recommends that customers upgrade to supported versions.”

The security patch for this vulnerability comes just about two weeks after Oracle’s regular Critical Patch Update (CPU) for October 2017, which patches a total of 252 vulnerabilities in its products, including 40 in Fusion Middleware out of which 26 are remotely exploitable without authentication.

DUHK Attack Lets Hackers Recover Encryption Key Used in VPNs & Web Sessions

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DUHK — Don’t Use Hard-coded Keys — is a new ‘non-trivial’ cryptographic implementation vulnerability that could allow attackers to recover encryption keys that secure VPN connections and web browsing sessions.

DUHK is the third crypto-related vulnerability reported this month after KRACK Wi-Fi attack and ROCA factorization attack.

The vulnerability affects products from dozens of vendors, including Fortinet, Cisco, TechGuard, whose devices rely on ANSI X9.31 RNG — an outdated pseudorandom number generation algorithm — ‘in conjunction with a hard-coded seed key.’

Before getting removed from the list of FIPS-approved pseudorandom number generation algorithms in January 2016, ANSI X9.31 RNG was included into various cryptographic standards over the last three decades.

Pseudorandom number generators (PRNGs) don’t generate random numbers at all. Instead, it is a deterministic algorithm that produces a sequence of bits based on initial secret values called a seed and the current state. It always generates the same sequence of bits for when used with same initial values.

Some vendors store this ‘secret’ seed value hard-coded into the source code of their products, leaving it vulnerable to firmware reverse-engineering.

Discovered by cryptography researchers — Shaanan Cohney, Nadia Heninger, and Matthew Green — DUHK, a ‘state recovery attack,’ allows man-in-the-middle attackers, who already know the seed value, to recover the current state value after observing some outputs.

Using both values in hand, attackers can then use them to re-calculate the encryption keys, allowing them to recover encrypted data that could ‘include sensitive business data, login credentials, credit card data and other confidential content.

“In order to demonstrate the practicality of this attack, we develop a full passive decryption attack against FortiGate VPN gateway products using FortiOS version 4.” researchers said.

“Our scans found at least 23,000 devices with a publicly visible IPv4 address running a vulnerable version of FortiOS.”

Here below you can check a partial list (tested by researchers) of affected devices from various vendors:

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The security researchers have released a brief blog post and technical researcher paper on a dedicated website for DUHK attack.

Serious Crypto-Flaw Lets Hackers Recover Private RSA Keys Used in Billions of Devices

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If you think KRACK attack for WiFi is the worst vulnerability of this year, then hold on…

…we have got another one for you which is even worse.

Microsoft, Google, Lenovo, HP and Fujitsu are warning their customers of a potentially serious vulnerability in widely used RSA cryptographic library produced by German semiconductor manufacturer Infineon Technologies.

It’s noteworthy that this crypto-related vulnerability (CVE-2017-15361) doesn’t affect elliptic-curve cryptography and the encryption standard itself, rather it resides in the implementation of RSA key pair generation by Infineon’s Trusted Platform Module (TPM).

Infineon’s Trusted Platform Module (TPM) is a widely-used, dedicated microcontroller designed to secure hardware by integrating cryptographic keys into devices and is used for secured crypto processes.

This 5-year-old algorithmic vulnerability was discovered by security researchers at Masaryk University in the Czech Republic, who have released a blog post with more details about the weakness as well as an online tool to test if RSA keys are vulnerable to this dangerous flaw.

ROCA: Factorization Attack to Recover Private RSA Keys

Dubbed ROCA (Return of Coppersmith’s Attack), the factorization attack introduced by the researchers could potentially allow a remote attacker to reverse-calculate a private encryption key just by having a target’s public key—thanks to this bug.

“Only the knowledge of a public key is necessary and no physical access to the vulnerable device is required,” the researchers said. “The vulnerability does NOT depend on a weak or a faulty random number generator—all RSA keys generated by a vulnerable chip are impacted.”

This could eventually allow the attacker to impersonate key owner, decrypt victim’s sensitive data, inject malicious code into digitally signed software, and bypass protections that prevent accessing or tampering with the targeted computer.

ROCA Attack Exposes Billions of Devices to Attack

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The ROCA attack affects chips manufactured by Infineon as early as 2012 and is feasible for key lengths, including 1024 and 2048 bits, which is most commonly used in the national identity cards, on PC motherboards to securely store passwords, in authentication tokens, during secure browsing, during software and application signing, and with message protection like PGP.

The flaw also weakens the security of government and corporate computers protected using Infineon’s cryptographic library and chips.

Majority of Windows and Google Chromebook devices developed by HP, Lenovo and Fujitsu are amongst those affected by the ROCA attack.

“We found and analyzed vulnerable keys in various domains including electronic citizen documents, authentication tokens, trusted boot devices, software package signing, TLS/HTTPS keys and PGP,” the researchers said. 

“The currently confirmed number of vulnerable keys found is about 760,000 but possibly up to two to three magnitudes more are vulnerable.”

More Details, Testing Tool, and Patches

The security researchers have released a brief blog post about the flaw, which includes a number of tools for detection, mitigation and workarounds.

The vulnerability was discovered and reported to Infineon Technologies in February this year and the researchers will present their full findings, including the factorization method, on November 2nd at the ACM Conference on Computer and Communications Security.

Their research paper, titled “The Return of Coppersmith’s Attack: Practical Factorization of Widely Used RSA Moduli” (ROCA), will also be released after their presentation.

So, companies and organisations have enough time to change affected encryption keys before the details of how this vulnerability works and could be exploited are released.

Major vendors including InfineonMicrosoft, Google, HP, Lenovo, and Fujitsu have already released the software updates for their relevant hardware and software as well as guidelines for a mitigation of this vulnerability.

“Some Windows security features and potentially third-party software rely on keys generated by the TPM (if available on the system),” according to a Microsoft advisory. “Microsoft is releasing Windows security updates to help work around the vulnerability by logging events and by allowing the generation of software based keys.”

Therefore, users are strongly recommended to patch their devices as soon as possible—AGAIN!

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