Title: Apache Web Server ETag Header Information Disclosure Weakness
Severity: HIGH
Description:
Apache is a freely available web server. It is available for a variety of platforms including the Unix, Linux and, Microsoft Windows operating systems.
A cache management feature is available for Apache that makes use of an entity tag (ETag) header. When this option is enabled and a request is made for a document relating to a file, for caching purposes, an ETag response header is returned containing various file attributes. ETag information allows further requests for files to contain specific information, such as the file's inode number, which allows for faster lookup times.
A weakness has been found in the generation of ETag headers under certain configurations implementing the FileETag directive. Among the file attributes included in the header is the file inode number that is returned to a client. This poses a security risk, as this information may aid in launching attacks against other network-based services. For instance, NFS uses inode numbers to generate file handles.
OpenBSD has released a patch that addresses this issue. Inode numbers returned from the server are now encoded using a private hash to avoid the release of sensitive information.
Apache 1.3.22 and earlier are not configurable to disable the use of inodes in ETag headers. However, default behaviour in later versions will still release this sensitive information.
Affected Products:
- Apache Software Foundation Apache 1.3.22
- Apache Software Foundation Apache 1.3.23
- Apache Software Foundation Apache 1.3.24
- Apache Software Foundation Apache 1.3.25
- Apache Software Foundation Apache 1.3.26
- Apache Software Foundation Apache 1.3.27
- Caldera OpenLinux Server 3.1.0
- Caldera OpenLinux Server 3.1.1
- Caldera OpenLinux Workstation 3.1.0
- Caldera OpenLinux Workstation 3.1.1
- Conectiva Linux 6.0.0
- Conectiva Linux 7.0.0
- Conectiva Linux 8.0.0
- Debian Linux 3.0.0 alpha
- Debian Linux 3.0.0 arm
- Debian Linux 3.0.0 hppa
- Debian Linux 3.0.0 ia-32
- Debian Linux 3.0.0 ia-64
- Debian Linux 3.0.0 m68k
- Debian Linux 3.0.0 mips
- Debian Linux 3.0.0 mipsel
- Debian Linux 3.0.0 ppc
- Debian Linux 3.0.0 s/390
- Debian Linux 3.0.0 sparc
- HP HP-UX (VVOS) 11.0.0 4
- HP VirtualVault 4.5.0
- HP VirtualVault 4.6.0
- HP Webproxy 2.0.0
- Immunix Immunix OS 7+
- MandrakeSoft Corporate Server 1.0.1
- MandrakeSoft Corporate Server 2.1.0
- MandrakeSoft Corporate Server 2.1.0 x86_64
- MandrakeSoft Linux Mandrake 7.2.0
- MandrakeSoft Linux Mandrake 8.0.0
- MandrakeSoft Linux Mandrake 8.0.0 ppc
- MandrakeSoft Linux Mandrake 8.1.0
- MandrakeSoft Linux Mandrake 8.1.0 ia64
- MandrakeSoft Linux Mandrake 8.2.0
- MandrakeSoft Linux Mandrake 8.2.0 ppc
- MandrakeSoft Linux Mandrake 9.0.0
- MandrakeSoft Linux Mandrake 9.1.0
- MandrakeSoft Linux Mandrake 9.1.0 ppc
- OpenBSD OpenBSD 3.1
- OpenBSD OpenBSD 3.2
- OpenBSD OpenBSD 3.3
- OpenPKG OpenPKG 1.0.0
- OpenPKG OpenPKG 1.1.0
- OpenPKG OpenPKG Current
- Oracle Oracle HTTP Server 9.0.1
- Oracle Oracle HTTP Server 9.2.0 .0
- Oracle Oracle9i Application Server 1.0.2
- Oracle Oracle9i Application Server 1.0.2 .1s
- Oracle Oracle9i Application Server 1.0.2 .2
- Oracle Oracle9i Application Server 9.0.2
- RedHat Enterprise Linux AS 2.1
- RedHat Enterprise Linux AS 2.1 IA64
- RedHat Enterprise Linux ES 2.1
- RedHat Enterprise Linux ES 2.1 IA64
- RedHat Enterprise Linux WS 2.1
- RedHat Enterprise Linux WS 2.1 IA64
- RedHat Linux 6.2.0 alpha
- RedHat Linux 6.2.0 i386
- RedHat Linux 6.2.0 sparc
- RedHat Linux 7.0.0 alpha
- RedHat Linux 7.0.0 i386
- RedHat Linux 7.1.0 alpha
- RedHat Linux 7.1.0 i386
- RedHat Linux 7.1.0 ia64
- RedHat Linux 7.2.0 i386
- RedHat Linux 7.2.0 ia64
- RedHat Linux 7.3.0
- RedHat Linux 7.3.0 i386
- RedHat Linux Advanced Work Station 2.1.0
- S.u.S.E. Linux 8.0.0
- S.u.S.E. Linux 8.0.0 i386
- SGI IRIX 6.5.19
- Slackware Linux 8.1.0
- Trustix Secure Linux 1.1.0
- Trustix Secure Linux 1.2.0
- Trustix Secure Linux 1.5.0
- Unisphere Networks SDX-300 2.0.3
References:
- Apache Software Foundation: Core Feature: FileETag Directive
- Novell: TID10090670 Potential Apache Security Vulnerability discloses iNode information
- OpenBSD: OpenBSD 3.2 release errata & patch list
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