Firefox 3.6.9 fixes numerous security issues

Mozilla released Firefox 3.6.9 that fixes several security issues as well as stability issues.

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.

Frameset integer overflow vulnerability
The implementation of the HTML frameset element contained an integer overflow vulnerability. The code responsible for parsing the frameset columns used an 8-byte counter for the column numbers, so when a very large number of columns was passed in the counter would overflow. When this counter was subsequently used to allocate memory for the frameset, the memory buffer would be too small, potentially resulting in a heap buffer overflow and execution of attacker-controlled memory.

Dangling pointer vulnerability using DOM plugin array
There is a dangling pointer vulnerability in the implementation of navigator.plugins in which the navigator object could retain a pointer to the plugins array even after it had been destroyed. An attacker could potentially use this issue to crash the browser and run arbitrary code on a victim’s computer.

Windows XP DLL loading vulnerability
Firefox could be used to load a malicious code library that had been planted on a victim’s computer. Firefox attempts to load dwmapi.dll upon startup as part of its platform detection, so on systems that don’t have this library, such as Windows XP, Firefox will subsequently attempt to load the library from the current working directory. An attacker could use this vulnerability to trick a user into downloading a HTML file and a malicious copy of dwmapi.dll into the same directory on their computer and opening the HTML file with Firefox, thus causing the malicious code to be executed. If the attacker was on the same network as the victim, the malicious DLL could also be loaded via a UNC path. The attack also requires that Firefox not currently be running when it is asked to open the HTML file and accompanying DLL.

Heap buffer overflow in nsTextFrameUtils::TransformText
A heap buffer overflow in code routines is responsible for transforming text runs. A page could be constructed with a bidirectional text run which upon reflow could result in an incorrect length being calculated for the run of text. When this value is subsequently used to allocate memory for the text too small a buffer may be created potentially resulting in a buffer overflow and the execution of attacker controlled memory.

Dangling pointer vulnerability in nsTreeSelection
There was a remaining dangling pointer issue leftover from the fix to CVE-2010-2753. Under certain circumstances one of the pointers held by a XUL tree selection could be freed and then later reused, potentially resulting in the execution of attacker-controlled memory.

XUL tree removal crash and remote code execution
XUL objects could be manipulated such that the setting of certain properties on the object would trigger the removal of the tree from the DOM and cause certain sections of deleted memory to be accessed. In products based on Gecko version 1.9.2 (Firefox 3.6, Thunderbird 3.1) and newer this memory has been overwritten by a value that will cause an unexploitable crash. In products based on Gecko version 1.9.1 (Firefox 3.5, Thunderbird 3.0, and SeaMonkey 2.0) and older an attacker could potentially use this vulnerability to crash a victim’s browser and run arbitrary code on their computer.

Dangling pointer vulnerability in nsTreeContentView
The implementation of XUL < tree >‘s content view contains a dangling pointer vulnerability. One of the content view’s methods for accessing the internal structure of the tree could be manipulated into removing a node prior to accessing it, resulting in the accessing of deleted memory. If an attacker can control the contents of the deleted memory prior to its access they could use this vulnerability to run arbitrary code on a victim’s machine.

Crash and remote code execution in normalizeDocument
Code used to normalize a document contained a logical flaw that could be leveraged to run arbitrary code. When the normalization code ran, a static count of the document’s child nodes was used in the traversal, so a page could be constructed that would remove DOM nodes during this normalization which could lead to the accessing of a deleted object and potentially the execution of attacker-controlled memory.

Crash on Mac using fuzzed font in data: URL
A specially crafted font could be applied to a document and cause a crash on Mac systems. The crash showed signs of memory corruption and presumably could be used by an attacker to execute arbitrary code on a victim’s computer.

SJOW creates scope chains ending in outer object
The wrapper class XPCSafeJSObjectWrapper (SJOW), a security wrapper that allows content-defined objects to be safely accessed by privileged code, creates scope chains ending in outer objects. Users of SJOWs which expect the scope chain to end on an inner object may be handed a chrome privileged object which could be leveraged to run arbitrary JavaScript with chrome privileges.

UTF-7 XSS by overriding document charset using object type attribute
The type attribute of an object tag can override the charset of a framed HTML document, even when the document is included across origins. A page could be constructed containing such an tag which sets the charset of the framed document to UTF-7. This could potentially allow an attacker to inject UTF-7 encoded JavaScript into a site, bypassing the site’s XSS filters, and then executing the code using the above technique.

Copy-and-paste or drag-and-drop into designMode document allows XSS
When an HTML selection containing JavaScript is copy-and-pasted or dropped onto a document with designMode enabled the JavaScript will be executed within the context of the site where the code was dropped. A malicious site could leverage this issue in an XSS attack by persuading a user into taking such an action and in the process running malicious JavaScript within the context of another site.

Information leak via XMLHttpRequest statusText
The statusText property of an XMLHttpRequest object is readable by the requestor even when the request is made across origins. This status information reveals the presence of a web server and could be used to gather information about servers on internal private networks.

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Firefox 3.6.9 fixes numerous security issues