Linux Security
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Linux Security

Debian: 'fsh' symlink attack

Date 29 Nov 2000
2949
Posted By LinuxSecurity Advisories
New fsh packages exist to fix potential symlink attack vulnerabilities.

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Debian Security Advisory DSA-002-1                   This email address is being protected from spambots. You need JavaScript enabled to view it. 
https://www.debian.org/security/                         Wichert Akkerman
November 30, 2000
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Package        : fsh
Problem type   : symlink attack
Debian-specific: no

Colin Phipps found an interesting symlink attack problem in fsh (a
tool to quickly run remote commands over rsh/ssh/lsh). When fshd
starts it creates a directory in /tmp to hold its sockets. It tries
to do that securely by checking of it can chown that directory if
it already exists to check if it is owner by the user invoking it.
However an attacker can circumvent this check by inserting a
symlink to a file that is owner by the user who runs fhsd and
replacing that with a directory just before fshd creates the
socket.

This has been fixed in version 1.0.post.1-3potato.

wget url
        will fetch the file for you
dpkg -i file.deb
        will install the referenced file.


Debian GNU/Linux 2.2 alias potato
- ---------------------------------

  Potato was released for alpha, arm, i386, m68k, powerpc and sparc.


  Source archives:
     https://security.debian.org/dists/stable/updates/main/source/fsh_1.0.post.1-3potato.diff.gz
      MD5 checksum: 278a82a3899974ec60b4f92d3a2d53d7
     https://security.debian.org/dists/stable/updates/main/source/fsh_1.0.post.1-3potato.dsc
      MD5 checksum: d2e6eee08ba39ed82b756f39da2a1587
     https://security.debian.org/dists/stable/updates/main/source/fsh_1.0.post.1.orig.tar.gz
      MD5 checksum: d0ade4d65da92256c110a042479109f1

  Alpha architecture:
     https://security.debian.org/dists/stable/updates/main/binary-alpha/fsh_1.0.post.1-3potato_alpha.deb
      MD5 checksum: 729414dcde81ef4d50681839a8df62a2

  ARM architecture:
     https://security.debian.org/dists/stable/updates/main/binary-arm/fsh_1.0.post.1-3potato_arm.deb
      MD5 checksum: 5543a9a61b7af9b48c277f4aca83c75a

  Intel ia32 architecture:
     https://security.debian.org/dists/stable/updates/main/binary-i386/fsh_1.0.post.1-3potato_i386.deb
      MD5 checksum: 6d6dd446e87bff6ed57c7176813609c8

  Motorola 680x0 architecture:
     https://security.debian.org/dists/stable/updates/main/binary-m68k/fsh_1.0.post.1-3potato_m68k.deb
      MD5 checksum: 50bce3a431b141e68a3dfdae1b71f5a9

  PowerPC architecture:
     https://security.debian.org/dists/stable/updates/main/binary-powerpc/fsh_1.0.post.1-3potato_powerpc.deb
      MD5 checksum: 8e99a4a3657fee8d9545099d02526c5b

  Sun Sparc architecture:
     https://security.debian.org/dists/stable/updates/main/binary-sparc/fsh_1.0.post.1-3potato_sparc.deb
      MD5 checksum: fe3de98286cb7d5e83ca00631785adbe

  These files will be moved into
   ftp://ftp.debian.org/debian/dists/stable/*/binary-$arch/ soon.

For not yet released architectures please refer to the appropriate
directory  ftp://ftp.debian.org/debian/dists/sid/binary-$arch/ .

- -- 
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apt-get: deb  https://security.debian.org/ stable/updates main
dpkg-ftp:  ftp://security.debian.org/debian-security dists/stable/updates/main
Mailing list: This email address is being protected from spambots. You need JavaScript enabled to view it.

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