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iDEFENSE Security Advisory 12.21.04: libtiff STRIPOFFSETS Integer Overflow Vulnerability

libtiff STRIPOFFSETS Integer Overflow VulnerabilityiDEFENSE Security Advisory 12.21.04www.idefense.com/application/poi/display?id=173&type=vulnerabilitiesDecember 21, 2004I. BACKGROUNDlibtiff provides support for the Tag Image File Format (TIFF), a widely used format for storing image data.More information is available at the following site:http://www.remotesensing.org/libtiff/II. DESCRIPTIONRemote exploitation of an integer overflow in libtiff may allow for the execution of arbitrary code.The overflow occurs in the parsing of TIFF files set with the STRIPOFFSETS flag in libtiff/tif_dirread.c. In the TIFFFetchStripThing()function, the number of strips (nstrips) is used directly in a CheckMalloc() routine without sanity checking. The call ultimately boilsdown to:malloc(user_supplied_int*size(int32));When supplied 0x40000000 as the user supplied integer, malloc is called with a length argument of 0. This has the effect of returning the smallest possible malloc chunk. A user controlled buffer is subsequentlycopied to that small heap buffer, causing a heap overflow.When exploited, it is possible to overwrite heap structures and seize control of execution.III. ANALYSISAn attacker can exploit the above-described vulnerability to execute arbitrary code under the permissions of the target user. Successful exploitation requires that the attacker convince the end user to open the malicious TIFF file using an application linked with a vulnerable version of libtiff. Exploitation of this vulnerability against a remote target is difficult because of the precision required in the attack.IV. DETECTIONiDEFENSE has confirmed this vulnerability in libtiff 3.6.1. Changes wereintroduced in libtiff 3.7.0 that had the effect of fixing this vulnerability.The following vendors provide susceptible libtiff packages within their respective operating system distributions:                 - Gentoo Linux         - Fedora Linux         - RedHat Linux         - SuSE Linux         - Debian Linux V. WORKAROUNDOnly open TIFF files from trusted users.VI. VENDOR RESPONSEThis issue is addressed in libtiff 3.7.0 and 3.7.1.VII. CVE INFORMATIONA Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has notbeen assigned yet.VIII. DISCLOSURE TIMELINE12/15/2004  Discovery of fix in later software version12/21/2004  Public disclosureIX. CREDITinfamous41md[at]hotpop.com is credited with this discovery.Get paid for vulnerability researchhttp://www.idefense.com/poi/teams/vcp.jspX. LEGAL NOTICESCopyright (c) 2004 iDEFENSE, Inc.Permission is granted for the redistribution of this alertelectronically. It may not be edited in any way without the expresswritten consent of iDEFENSE. If you wish to reprint the whole or anypart of this alert in any other medium other than electronically, pleaseemail customerservice () idefense com for permission.Disclaimer: The information in the advisory is believed to be accurateat the time of publishing based on currently available information. Useof the information constitutes acceptance for use in an AS IS condition.There are no warranties with regard to this information. Neither theauthor nor the publisher accepts any liability for any direct, indirect,or consequential loss or damage arising from use of, or reliance on,this information.

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• iDEFENSE Security Advisory 12.21.04: libtiff STRIPOFFSETS Integer Overflow Vulnerabilitycustomer service mailbox (Dec 21)
  • Re: iDEFENSE Security Advisory 12.21.04: libtiff STRIPOFFSETS Integer Overflow VulnerabilityDmitry V. Levin (Dec 22)
  • Re: iDEFENSE Security Advisory 12.21.04: libtiff STRIPOFFSETS Integer Overflow VulnerabilityMoritz Muehlenhoff (Dec 23)
  • Re: iDEFENSE Security Advisory 12.21.04: libtiff STRIPOFFSETS Integer Overflow VulnerabilityMarcus Meissner (Dec 28)