rsync: Execution of arbitrary code

1.  Gentoo Linux Security Advisory

Version Information

Related bugreports: #216887

Synopsis

A buffer overflow in rsync might lead to the remote execution of arbitrary code when extended attributes are being used.

2.  Impact Information

Background

rsync is a file transfer program to keep remote directories synchronized.

Description

Sebastian Krahmer of SUSE reported an integer overflow in the expand_item_list() function in the file util.c which might lead to a heap-based buffer overflow when extended attribute (xattr) support is enabled.

Impact

A remote attacker could send a file containing specially crafted extended attributes to an rsync deamon, or entice a user to sync from an rsync server containing specially crafted files, possibly leading to the execution of arbitrary code.

Please note that extended attributes are only enabled when USE="acl" is enabled, which is the default setting.

3.  Resolution Information

Workaround

Disable extended attributes in the rsync daemon by setting "refuse options = xattrs" in the file "/etc/rsyncd.conf" (or append "xattrs" to an existing "refuse" statement). When synchronizing to a server, do not provide the "-X" parameter to rsync. You can also disable the "acl" USE flag for rsync and recompile the package.

Resolution

All rsync users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/rsync-2.6.9-r6"

4.  References

• CVE-2008-1720