Nedostaci su otkriveni u funkcijama "png_format_buffer", "png_rgb_to_gray" i "png_handle_sCAL", a očituju se kao korupcija memorije, preljev međuspremnika i nepravilno rukovanje sCAL dijelovima u PNG slici.
Posljedica:
Pomoću posebno oblikovane PNG slike, udaljeni napadač može iskoristiti navedene nedostatke kako bi izveo DoS napad i pokrenuo proizvoljni programski kod.
Rješenje:
Preporuča se korištenje odgovarajućih programskih zakrpa.
==========================================================================
Ubuntu Security Notice USN-1175-1
July 26, 2011
libpng vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 11.04
- Ubuntu 10.10
- Ubuntu 10.04 LTS
- Ubuntu 8.04 LTS
Summary:
Libpng could be made to run programs as your login if it opened a
specially crafted file.
Software Description:
- libpng: PNG (Portable Network Graphics) file library
Details:
Frank Busse discovered that libpng did not properly handle certain
malformed PNG images. If a user or automated system were tricked into
opening a crafted PNG file, an attacker could cause libpng to crash,
resulting in a denial of service. This issue only affected Ubuntu
10.04 LTS, 10.10, and 11.04. (CVE-2011-2501)
It was discovered that libpng did not properly handle certain malformed PNG
images. If a user or automated system were tricked into opening a crafted
PNG file, an attacker could cause a denial of service or possibly execute
arbitrary code with the privileges of the user invoking the program.
(CVE-2011-2690)
Frank Busse discovered that libpng did not properly handle certain PNG
images with invalid sCAL chunks. If a user or automated system were tricked
into opening a crafted PNG file, an attacker could cause a denial of
service or possibly execute arbitrary code with the privileges of the user
invoking the program. (CVE-2011-2692)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 11.04:
libpng12-0 1.2.44-1ubuntu3.1
Ubuntu 10.10:
libpng12-0 1.2.44-1ubuntu0.1
Ubuntu 10.04 LTS:
libpng12-0 1.2.42-1ubuntu2.2
Ubuntu 8.04 LTS:
libpng12-0 1.2.15~beta5-3ubuntu0.4
After a standard system update you need to reboot your computer to make
all the necessary changes.
References:
http://www.ubuntu.com/usn/usn-1175-1
CVE-2011-2501, CVE-2011-2690, CVE-2011-2692
Package Information:
https://launchpad.net/ubuntu/+source/libpng/1.2.44-1ubuntu3.1
https://launchpad.net/ubuntu/+source/libpng/1.2.44-1ubuntu0.1
https://launchpad.net/ubuntu/+source/libpng/1.2.42-1ubuntu2.2
https://launchpad.net/ubuntu/+source/libpng/1.2.15~beta5-3ubuntu0.4
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