Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.


06:50 AM
Connect Directly

MOBB Bug Among Mozilla Patches

Fix avoids 'race conditions,' where a system tries to perform multiple operations simultaneously, bypassing normal processing

Among a round of security patches issued yesterday by Mozilla in a new version of its Firefox browser was a critical one first discovered by the head researcher of the Month of Browser Bugs (MOBB) project. (See Getting Buggy with the MOBB.)

The vulnerability in the Firefox browser allows a so-called "race condition" in JavaScript's garbage collector, which lets an attacker execute arbitrary code and ultimately load adware and malware, or destroy the hard disk. A race condition is when a system tries to perform two or more operations simultaneously, which wreaks havoc because they must be done in the proper sequence.

But HD Moore, the researcher who heads up MOBB and found the Firefox bug, as of press time had not yet published the bug on his site. He had agreed to hold off until after Mozilla had released the updates to its browser. The MOBB project, although well-respected, has faced some criticism on publishing bugs before vendors have patched the problems.

Mozilla released the new Firefox version, which patches the JavaScript bug as well as 12 other vulnerabilities, 7 of those which Mozilla categorized as "critical," a day after alerting users of vulnerabilities. Among the other vulnerabilities patched in the new version are cross-site scripting, heap overflow, privilege access, JavaScript engine, and object vulnerabilities.

"We strongly recommend that all users upgrade to this latest release," Chris Beard, vice president of products for Mozilla said in a statement.

Moore, meanwhile, says he found the JavaScript race condition while working with a Firefox-specific fuzzer. A fuzzer is a program that tries to find security holes, typically by sending random input to an application to see how it reacts.

The race condition caused the JavaScript garbage collector to delete some code that then can be used to run malware, for instance. "Once you trigger the bug, code execution is easy," Moore says. "With enough work, it could be made into a very reliable code execution exploit, but someone has to find a way to reliably trigger the garbage collector at the right time."

Moore says his test script still needs some work, but he'll likely post it on the MOBB site soon. An attack using this vulnerability occurs in two stages: "First, you load multiple copies of the payload into memory and cause the target address to be allocated," he says. "Then you try to trigger the race condition that results in the program jumping to the payload."

Marc Maiffret, CTO for eEye Digital Security, which sells Blink, an endpoint intrusion-prevention system, says the Mozilla patches overall look like "more of the same" browser vulnerabilities out there today. But it's these non-Microsoft vulnerabilities that worry him most. "The scariest thing in security is the average company running predominantly Windows desktops or servers are so focused on Microsoft Patch Tuesday that they've forgotten most of the other software on their network," he says. "These are just as vulnerable if not more."

— Kelly Jackson Higgins, Senior Editor, Dark Reading

  • Mozilla
  • eEye Digital Security Kelly Jackson Higgins is the Executive Editor of Dark Reading. She is an award-winning veteran technology and business journalist with more than two decades of experience in reporting and editing for various publications, including Network Computing, Secure Enterprise ... View Full Bio

    Recommended Reading:

    Comment  | 
    Print  | 
    More Insights
  • Comments
    Newest First  |  Oldest First  |  Threaded View
    COVID-19: Latest Security News & Commentary
    Dark Reading Staff 6/4/2020
    Data Loss Spikes Under COVID-19 Lockdowns
    Seth Rosenblatt, Contributing Writer,  5/28/2020
    Abandoned Apps May Pose Security Risk to Mobile Devices
    Robert Lemos, Contributing Writer,  5/29/2020
    Register for Dark Reading Newsletters
    White Papers
    Cartoon Contest
    Write a Caption, Win a Starbucks Card! Click Here
    Latest Comment: What? IT said I needed virus protection!
    Current Issue
    How Cybersecurity Incident Response Programs Work (and Why Some Don't)
    This Tech Digest takes a look at the vital role cybersecurity incident response (IR) plays in managing cyber-risk within organizations. Download the Tech Digest today to find out how well-planned IR programs can detect intrusions, contain breaches, and help an organization restore normal operations.
    Flash Poll
    Twitter Feed
    Dark Reading - Bug Report
    Bug Report
    Enterprise Vulnerabilities
    From DHS/US-CERT's National Vulnerability Database
    PUBLISHED: 2020-06-04
    ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows remote attackers to cause a denial of service (daemon exit or system time change) by predicting transmit timestamps for use in spoofed packets. The victim must be relying on unauthenticated IPv4 time sources. There must be an off-path attac...
    PUBLISHED: 2020-06-04
    In Zoho ManageEngine OpManager before 125144, when <cachestart> is used, directory traversal validation can be bypassed.
    PUBLISHED: 2020-06-04
    An improper neutralization of input vulnerability in the Admin Profile of FortiAnalyzer may allow a remote authenticated attacker to perform a stored cross site scripting attack (XSS) via the Description Area.
    PUBLISHED: 2020-06-04
    An unquoted service path vulnerability in the FortiSIEM Windows Agent component may allow an attacker to gain elevated privileges via the AoWinAgt executable service path.
    PUBLISHED: 2020-06-04
    Use of a hard-coded cryptographic key to encrypt security sensitive data in local storage and configuration in FortiClient for Windows prior to 6.4.0 may allow an attacker with access to the local storage or the configuration backup file to decrypt the sensitive data via knowledge of the hard-coded ...