Firefox Dirty Dozen: Mozilla Fixes Critical Browser Flaws

Mozilla has released Firefox 3.6.11 with patches for a dozen security holes, some serious enough to launch attacks if a user simply surfs to a booby-trapped website.

Mozilla has released Firefox 3.6.11 with patches for a dozen security holes, some serious enough to launch attacks if a user simply surfs to a booby-trapped website.

In all, the open-source released nine bulletins documenting 12 security vulnerabilities. Five of the bulletins are rated “critical,” meaning that those vulnerabilities can be exploited to run attacker code and install software, requiring no user interaction beyond normal browsing.

Here’s the raw information on the critical updates:

MFSA 2010-71 Unsafe library loading vulnerabilities:

Mozilla developer Ehsan Akhgari reported that a function used to load external libraries on Windows platforms was using a relative path to a DLL-loading application and was thus vulnerable to binary planting if an attacker was able to place an executable of the same name in the current working directory or any of the other locations that Windows searches for executables.

Dmitri Gribenko reported that the script used to launch Mozilla applications on Linux was effectively including the current working directory in the LD_LIBRARY_PATH environment variable. If an attacker was able to place into the current working directory a malicious shared library with the same name as a library that the bootstrapping script depends on the attacker could have their library loaded instead of the legitimate library.

MFSA 2010-67
Dangling pointer vulnerability in LookupGetterOrSetter:

Security researcher regenrecht reported that when window.__lookupGetter__ is called with no arguments the code assumes the top JavaScript stack value is a property name. Since there were no arguments passed into the function, the top value could represent uninitialized memory or a pointer to a previously freed JavaScript object. Under such circumstances the value is passed to another subroutine which calls through the dangling pointer, potentially executing attacker-controlled memory.

MFSA 2010-66 Use-after-free error in nsBarProp

Security researcher Sergey Glazunov reported that it was possible to access the locationbar property of a window object after it had been closed. Since the closed window’s memory could have been subsequently reused by the system it was possible that an attempt to access the locationbar property could result in the execution of attacker-controlled memory.

MFSA 2010-65 Buffer overflow and memory corruption using document.write

Security researcher Alexander Miller reported that passing an excessively long string to document.write could cause text rendering routines to end up in an inconsistent state with sections of stack memory being overwritten with the string data. An attacker could use this flaw to crash a victim’s browser and potentially run arbitrary code on their computer.

MFSA 2010-64 Miscellaneous memory safety hazards

Mozilla developers identified and fixed several memory safety bugs in the browser engine used in Firefox and other Mozilla-based products. Some of these bugs showed evidence of memory corruption under certain circumstances, and we presume that with enough effort at least some of these could be exploited to run arbitrary code.

The update is being shipped via the browser’s auto-update mechanism.

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