VULNERABILITIES MEETING
April 12, 1999
4:00 – 4:30pm
3085 ENG II
In attendance:
Matt Bishop (MB), Tuomas Aura (TA) and Todd Heberlein (TH)
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Symbolic Links
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Indirect aliases - instead of pointing to an inode, it points to another
name or inode.
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The goal is to formalize symbolic links to see whether eliminating or redefining
symbolic links reduces race conditions.

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Issues
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LPR is written
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Symbolic Links vs. Hard Links
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If treated as a hard link, would the vulnerabilities be different?
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Cannot chain hard links
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Symbolic Link - restricting length of chain
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What happens if target doesn't exist?
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Macintosh model - can't point to a pointer
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Could introduce new symbolic link

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Comments
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TA: The link looks like any other name - is it a file or a name? Is there
a way to evaluate attributes?
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MB: HPs and Iris symbolic links are different from DECs
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The semantics are not well settled; they are inconsistent between systems.
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Why would you change ownership of a symbolic link?
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TA: You should not be allowed to check permission of a pointer to an inode
or the object itself
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You need to resolve the name issue
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Access to object, permissions, properties
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Bind(fd, name)
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Open (fd)
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Secure bind - not follow any links?
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Sbind (fd, name w/o links)
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New API
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3-4 attacks involving finger - which systems have which semantics
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Are there similar problems in NT?
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Macro language
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Discuss Melissa virus at next Vulner meeting - it affected Window 98, 95,
NT and Macs.
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IT teaches classes in macro language