search

apple / cups

Apple CUPS Sources
https://www.cups.org
Apache License 2.0
1.93k stars 464 forks source link

ZDI-CAN-367: Apple CUPS 1.3.7 (HP-GL/2 filter) Remote Code Execution Vulnerability #2911

Closed michaelrsweet closed 16 years ago

michaelrsweet commented 16 years ago

Version: 1.3-current CUPS.org User: mike

-- ABSTRACT ------------------------------------------------------------

TippingPoint has identified a vulnerability affecting the following products:

Apple OS X

-- VULNERABILITY DETAILS -----------------------------------------------

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Apple CUPS. Authentication is not required to exploit this vulnerability.

The specific flaw exists in the Hewlett-Packard Graphics Language filter. Inadequate bounds checking on the pen width and pen color opcodes result in an arbitrary memory overwrite allowing for the execution of arbitrary code as the "hgltops" process uid.

From filter/hpgltops.h:

   typedef struct
   {
     float rgb[3]; /* Pen color */
     float width;  /* Pen width */
   } pen_t;

   VAR pen_t Pens[1024]; /* State of each pen */

From filter/hpgl-attr.c:PW_pen_width():

   float w;
   ...

[323] w = (float)hypot(PlotSize[0], PlotSize[1]) / 1016.0f * 72.0f;

   if (num_params == 0)
     w *= 0.01f;
   else

[328] w *= params[0].value.number; ... pen = (int)params[1].value.number;

[335] Pens[pen].width = w;

There is a lack of a check on user provided index value at line [355]. An attacker may control values of PlotSize[0] and PlotSize[1]. By selecting the opcode PS and pen width to 1.0 and provide appropriate multiplier later at line [328] an attacker can overwrite memory address with arbitrary data.

From filter/hpgl-attr.c:PC_pen_color():

   i = (int)params[0].value.number;
   ...
   Pens[i].rgb[0] = (params[1].value.number - ColorRange[0][0]) /
                    (ColorRange[0][1] - ColorRange[0][0]);
   Pens[i].rgb[1] = (params[2].value.number - ColorRange[1][0]) /
                    (ColorRange[1][1] - ColorRange[1][0]);
   Pens[i].rgb[2] = (params[3].value.number - ColorRange[2][0]) /
                    (ColorRange[2][1] - ColorRange[2][0]);

The same flaw exists here with the CR opcode.

-- CREDIT --------------------------------------------------------------

This vulnerability was discovered by: * regenrecht

-- FURTHER DETAILS -----------------------------------------------------

If you have any questions, comments, concerns or require additional details please feel free to contact me via the following:

Cameron Hotchkies
Security Response Lead
TippingPoint
chotchkies@tippingpoint.com
Office: 512.681.8172

Additionally, you may contact the manager of security response at:

Terri Forslof
Manager of Security Response
TippingPoint
tforslof@tippingpoint.com
Office: 206.618.7112

We can alternatively be reached via e-mail at:

zdi-disclosures@tippingpoint.com

Our PGP key is available from:

http://www.zerodayinitiative.com/documents/disclosures-pgp-key.asc

-- INFORMATION ABOUT THE ZDI -------------------------------------------

Established by TippingPoint, The Zero Day Initiative (ZDI) represents a best-of-breed model for rewarding security researchers for responsibly disclosing discovered vulnerabilities.

The ZDI is unique in how the acquired vulnerability information is used. TippingPoint does not re-sell the vulnerability details or any exploit code. Instead, upon notifying the affected product vendor, TippingPoint provides its customers with zero day protection through its intrusion prevention technology. Explicit details regarding the specifics of the vulnerability are not exposed to any parties until an official vendor patch is publicly available. Furthermore, with the altruistic aim of helping to secure a broader user base, TippingPoint provides this vulnerability information confidentially to security vendors (including competitors) who have a vulnerability protection or mitigation product.

Please contact us for further information or refer to:

http://www.zerodayinitiative.com

-- DISCLOSURE POLICY ---------------------------------------------------

Our vulnerability disclosure policy is available online at:

http://www.zerodayinitiative.com/advisories/disclosure_policy/
michaelrsweet commented 16 years ago

CUPS.org User: mike

Patch attached with fix...

michaelrsweet commented 16 years ago

CUPS.org User: mike

Fixed in Subversion repository.

michaelrsweet commented 16 years ago

"str2911.patch":

Index: filter/hpgl-attr.c

--- filter/hpgl-attr.c (revision 914) +++ filter/hpgl-attr.c (working copy) @@ -197,8 +197,18 @@

if (num_params == 0) PenCount = 8;

@@ -108,10 +116,10 @@ /* Current pen position / PenScaling VALUE(1.0f), / Pen width scaling factor / PenWidth VALUE(1.0f); / Default pen width _/ -VAR pent Pens[1024]; / State of each pen _/ +VAR pen_t Pens[MAXPENS]; / State of each pen / VAR int PenMotion VALUE(0), / 0 = absolute, 1 = relative / PenValid VALUE(0), / 1 = valid position, 0 = undefined */