Tag Archives: Vulnerability

CredSSP Flaw in Remote Desktop Protocol Affects All Versions of Windows

A critical vulnerability has been discovered in Credential Security Support Provider protocol (CredSSP) that affects all versions of Windows to date and could allow remote attackers to exploit RDP and WinRM to steal data and run malicious code.

CredSSP protocol has been designed to be used by RDP (Remote Desktop Protocol) and Windows Remote Management (WinRM) that takes care of securely


A Denial of Service vulnerability was found in Apache Qpid Broker-J 7.0.0 in functionality for authentication of connections for AMQP protocols 0-8, 0-9, 0-91 and 0-10 when PLAIN or XOAUTH2 SASL mechanism is used. The vulnerability allows unauthenticated attacker to crash the broker instance. AMQP 1.0 and HTTP connections are not affected. An authentication of incoming AMQP connections in Apache Qpid Broker-J is performed by special entities called “Authentication Providers”. Each Authentication Provider can support several SASL mechanisms which are offered to the connecting clients as part of SASL negotiation process. The client chooses the most appropriate SASL mechanism for authentication. Authentication Providers of following types supports PLAIN SASL mechanism: Plain, PlainPasswordFile, SimpleLDAP, Base64MD5PasswordFile, MD5, SCRAM-SHA-256, SCRAM-SHA-1. XOAUTH2 SASL mechanism is supported by Authentication Providers of type OAuth2. If an AMQP port is configured with any of these Authentication Providers, the Broker may be vulnerable. (CVSS:4.3) (Last Update:2018-03-10)

Hard-Coded Password in Cisco Software Lets Attackers Take Over Linux Servers

A medium yet critical vulnerability has been discovered in Cisco Prime Collaboration Provisioning software that could allow a local attacker to elevate privileges to root and take full control of a system.

Cisco Prime Collaboration Provisioning (PCP) application allows administrators to remotely control the installation and management of Cisco communication devices (integrated IP telephony,

Hackers Exploiting ‘Bitmessage’ Zero-Day to Steal Bitcoin Wallet Keys


Bitmessage developers have warned of a critical ‘remotely executable’ zero-day vulnerability in the PyBitmessage application that was being exploited in the wild.

Bitmessage is a Peer-to-Peer (P2P) communications protocol used to send encrypted messages to users. Since it is decentralized and trustless communications, one need-not inherently trust any entities like root certificate authorities.

Those who unaware, PyBitmessage is the official client for Bitmessage messaging service.

According to Bitmessage developers, a critical zero-day remote code execution vulnerability, described as a message encoding flaw, affects PyBitmessage version 0.6.2 for Linux, Mac, and Windows and has been exploited against some of their users.

“The exploit is triggered by a malicious message if you are the recipient (including joined chans). The attacker ran an automated script but also opened, or tried to open, a remote reverse shell,” Bitmessage core developer Peter Šurda explained in a Reddit thread.

“The automated script looked in ~/.electrum/wallets [Electrum wallets], but when using the reverse shell, he had access to other files as well. If the attacker transferred your Bitcoins, please contact me (here on Reddit).”

Moreover, hackers also targeted Šurda. Since his Bitmessage addresses were most likely considered to be compromised, he suggested users not to contact him at that address.

“My old Bitmessage addresses are to be considered compromised and not to be used,” Šurda tweeted.

Šurda believes that the attackers exploiting this vulnerability to gain remote access are primarily looking for private keys of Electrum bitcoin wallets stored on the compromised device, using which they could/might have stolen bitcoins.

Bitmessage developers have since fixed the vulnerability with the release of new PyBitmessage version

So, if you are running an affected version of PyBitmessage, you are highly recommended to upgrade your software to version

Since the vulnerability affects PyBitmessage version 0.6.2 and not PyBitmessage 0.6.1, alternatively you can also consider, as suggested by Šurda, downgrading your application to mitigate yourself from potential zero-day attacks.

Although the developers did not reveal more details about the critical vulnerability, Šurda advised users to change all their passwords and create new Bitmessage keys, if they have any suspicion of their computers being compromised.

Binary files for Windows and OSX are expected to become available on Wednesday.

The investigation into these attacks is still ongoing, and we will update this article with more information as it becomes available.

Stay Tuned! Stay Safe!

Microsoft Won’t Patch a Severe Skype Vulnerability Anytime Soon


A serious vulnerability has been discovered in Microsoft-owned most popular free web messaging and voice calling service Skype that could potentially allow attackers to gain full control of the host machine by granting system-level privileges to a local, unprivileged user.

The worst part is that this vulnerability will not be patched by Microsoft anytime soon.

It’s not because the flaw is unpatchable, but because fixing the vulnerability requires a significant software rewrite, which indicates that the company will need to issue an all-new version of Skype rather than just a patch.

The vulnerability has been discovered and reported to Microsoft by security researcher Stefan Kanthak and resides in Skype’s update installer, which is susceptible to Dynamic Link Libraries (DLL) hijacking.

According to the researcher, a potential attacker could exploit the “functionality of the Windows DLL loader where the process loading the DLL searches for the DLL to be loaded first in the same directory in which the process binary resides and then in other directories.”

The exploitation of this preferential search order would allow the attacker to hijack the update process by downloading and placing a malicious version of a DLL file into a temporary folder of a Windows PC and renaming it to match a legitimate DLL that can be modified by an unprivileged user without having any special account privileges.

When Skype’s update installer tries to find the relevant DLL file, it will find the malicious DLL first, and thereby will install the malicious code.

Although Kanthak demonstrated the attack using the Windows version of Skype, he believes the same DLL hijacking method could also work against other operating systems, including Skype versions for macOS and Linux.

Kanthak informed Microsoft of the Skype vulnerability back in September, but the company told him that the patch would require the Skype update installer go through “a large code revision,” Kanthak told ZDNet.

So rather than releasing a security update, Microsoft decided to build an altogether new version of the Skype client that would address the vulnerability.

It should be noted that this vulnerability only affects the Skype for the desktop app, which uses its update installer which is vulnerable to the DLL hijacking technique. The Universal Windows Platform (UWP) app version available from the Microsoft Store for Windows 10 PCs is not affected.

The vulnerability has been rated as “medium” in severity, but Kanthak said, “the attack could be easily weaponized.” He gave two examples, which have not been released yet.

Until the company issues an all-new version of Skype client, users are advised to exercise caution and avoid clicking on attachments provided in an email. Also, make sure you run appropriate and updated anti-virus software that offers some defence against such attacks.

This is not the first time Skype has been dealing with a severe security flaw. In June 2017, a critical flaw in Skype was revealed before Microsoft released a fix for the issue that allowed hackers to crash systems and execute malicious code in them.

Last month, among several messaging applications, Skype was also dealing with a critical remote code execution vulnerability in Electron—a popular web application framework widely-used in desktop applications.

Hackers Exploit ‘Telegram Messenger’ Zero-Day Flaw to Spread Malware


A zero-day vulnerability has been discovered in the desktop version for end-to-end encrypted Telegram messaging app that was being exploited in the wild in order to spread malware that mines cryptocurrencies such as Monero and ZCash.

The Telegram vulnerability was uncovered by security researcher Alexey Firsh from Kaspersky Lab last October and affects only the Windows client of Telegram messaging software.

The flaw has actively been exploited in the wild since at least March 2017 by attackers who tricked victims into downloading malicious software onto their PCs that used their CPU power to mine cryptocurrencies or serve as a backdoor for attackers to remotely control the affected machine, according to a blogpost on Securelist.

Here’s How Telegram Vulnerability Works

The vulnerability resides in the way Telegram Windows client handles the RLO (right-to-left override) Unicode character (U+202E), which is used for coding languages that are written from right to left, like Arabic or Hebrew.

According to Kaspersky Lab, the malware creators used a hidden RLO Unicode character in the file name that reversed the order of the characters, thus renaming the file itself, and send it to Telegram users.

For example, when an attacker sends a file named “photo_high_re*U+202E*gnp.js” in a message to a Telegram user, the file’s name rendered on the users’ screen flipping the last part.

Therefore, the Telegram user will see an incoming PNG image file (as shown in the below image) instead of a JavaScript file, misleading into downloading malicious files disguised as the image.

“As a result, users downloaded hidden malware which was then installed on their computers,” Kaspersky says in its press release published today.

Kaspersky Lab reported the vulnerability to Telegram and the company has since patched the vulnerability in its products, as the Russian security firm said: “at the time of publication, the zero-day flaw has not since been observed in messenger’s products.”

Hackers Used Telegram to Infect PCs with Cryptocurrency Miners


During the analysis, Kaspersky researchers found several scenarios of zero-day exploitation in the wild by threat actors. Primarily, the flaw was actively exploited to deliver cryptocurrency mining malware, which uses the victim’s PC computing power to mine different types of cryptocurrency including Monero, Zcash, Fantomcoin, and others.

While analyzing the servers of malicious actors, the researchers also found archives containing a Telegram’s local cache that had been stolen from victims.

In another case, cybercriminals successfully exploited the vulnerability to install a backdoor trojan that used the Telegram API as a command and control protocol, allowing hackers to gain remote access to the victim’s computer.

“After installation, it started to operate in a silent mode, which allowed the threat actor to remain unnoticed in the network and execute different commands including the further installation of spyware tools,” the firm added.

Firsh believes the zero-day vulnerability was exploited only by Russian cybercriminals, as “all the exploitation cases that [the researchers] detected occurring in Russia,” and a lot of artifacts pointed towards Russian cybercriminals.

The best way to protect yourself from such attacks is not to download or open files from unknown or untrusted sources.

The security firm also recommended users to avoid sharing any sensitive personal information in messaging apps and make sure to have a good antivirus software from reliable company installed on your systems.

Critical Flaw in Grammarly Spell Checker Could Let Attackers Steal Your Data


A critical vulnerability discovered in the Chrome and Firefox browser extension of the grammar-checking software Grammarly inadvertently left all 22 million users’ accounts, including their personal documents and records, vulnerable to remote hackers.

According to Google Project Zero researcher Tavis Ormandy, who discovered the vulnerability on February 2, the Chrome and Firefox extension of Grammarly exposed authentication tokens to all websites that could be grabbed by remote attackers with just 4 lines of JavaScript code.

In other words, any website a Grammarly user visits could steal his/her authentication tokens, which is enough to login into the user’s account and access every “documents, history, logs, and all other data” without permission.

“I’m calling this a high severity bug, because it seems like a pretty severe violation of user expectations,” Ormandy said in a vulnerability report. “Users would not expect that visiting a website gives it permission to access documents or data they’ve typed into other websites.”

Ormandy has also provided a proof-of-concept (PoC) exploit, which explains how one can easily trigger this serious bug to steal Grammarly user’s access token with just four lines of code.


This high-severity flaw was discovered on Friday and fixed early Monday morning by the Grammarly team, which, according to the researcher, is “a really impressive response time” for addressing such bugs.

Security updates are now available for both Chrome and Firefox browser extensions, which should get automatically updated without requiring any action by Grammarly users.

A Grammarly spokesperson also told in an email that the company has no evidence of users being compromised by this vulnerability.

“Grammarly resolved a security bug reported by Google’s Project Zero security researcher, Tavis Ormandy, within hours of its discovery. At this time, Grammarly has no evidence that any user information was compromised by this issue,” the spokesperson said. 

“We’re continuing to monitor actively for any unusual activity. The security issue potentially affected text saved in the Grammarly Editor. This bug did not affect the Grammarly Keyboard, the Grammarly Microsoft Office add-in, or any text typed on websites while using the Grammarly browser extension. The bug is fixed, and there is no action required by Grammarly users.”

Stay tuned for more updates.

Unpatched DoS Flaw Could Help Anyone Take Down WordPress Websites


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.

However, to make “load-scripts.php” work on the admin login page (wp-login.php) before login, WordPress authors did not keep any authentication in place, eventually making the feature accessible to anyone.

wordpress dos attack

Depending upon the plugins and modules you have installed, the load-scripts.php file selectively calls required JavaScript files by passing their names into the “load” parameter, separated by a comma, like in the following URL:


While loading the website, the ‘load-scripts.php’ (mentioned in the head of the page) tries to find each JavaScript file name given in the URL, append their content into a single file and then send back it to the user’s web browser.

How WordPress DoS Attack Works


According to the researcher, one can simply force load-scripts.php to call all possible JavaScript files (i.e., 181 scripts) in one go by passing their names into the above URL, making the targeted website slightly slow by consuming high CPU and server memory.

“There is a well-defined list ($wp_scripts), that can be requested by users as part of the load[] parameter. If the requested value exists, the server will perform an I/O read action for a well-defined path associated with the supplied value from the user,” Tawily says.

Although a single request would not be enough to take down the whole website for its visitors, Tawily used a proof-of-concept (PoC) python script, doser.py, which makes large numbers of concurrent requests to the same URL in an attempt to use up as much of the target servers CPU resources as possible and bring it down.

The Hacker News has verified the authenticity of the DoS exploit that successfully took down one of our demo WordPress websites running on a medium-sized VPS server.

“It is time to mention again that load-scripts.php does not require any authentication, an anonymous user can do so. After ~500 requests, the server didn’t respond at all any more, or returned 502/503/504 status code errors,” Tawily says.

However, attack from a single machine, with some 40 Mbps connection, was not enough to take down another demo website running on a dedicated server with high processing power and memory.


But that doesn’t mean the flaw is not effective against WordPress websites running over a heavy-server, as application-level attack generally requires a lot fewer packets and bandwidth to achieve the same goal—to take down a site.

So attackers with more bandwidth or a few bots can exploit this flaw to target big and popular WordPress websites as well.

No Patch Available  – Mitigation Guide

Along with the full disclosure, Tawily has also provided a video demonstration for the WordPress Denial of Service attack. You can watch the video to see the attack in action.

Knowing that DoS vulnerabilities are out-of-scope from the WordPress bug bounty program, Tawily responsibly reported this DoS vulnerability to the WordPress team through HackerOne platform.

However, the company refused to acknowledge the issue, saying that this kind of bug “should really get mitigated at the server end or network level rather than the application level,” which is outside of WordPress’s control.

The vulnerability seems to be serious because WordPress powers nearly 29 percent of the Web, placing millions of websites vulnerable to hackers and making them unavailable for their legitimate users.

For websites that can’t afford services offering DDoS protection against application-layer attacks, the researcher has provided a forked version of WordPress, which includes mitigation against this vulnerability.

However, I personally wouldn’t recommend users to install modified CMS, even if it is from a trusted source other than the original author.

Besides this, the researcher has also released a simple bash script that fixes the issue, in case you have already installed WordPress.