.
Last update: 1997-05-20
9945-2-26
Class: Defect situation
The standards states what it states, and conforming implementations
must conform to this. However, concerns have been raised about this
which are being referred to the Sponsors of the standard for consideration as
a future amendment.
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Topic: write
Relevant Sections: 5.37.2
Defect Report:
In Section 5.37.2 - Description {of write}, the standard
states that ``[t]yping [other] nonprintable characters shall
cause implementation-defined sequences of printable
characters to be written to the recipient's terminal.''
[Draft 12 of ISO/IEC 9945-2:1993 (July 1992), p. 694, lines
5988-5989] and that ``[t]yping characters from LC_CTYPE
classifications print or space shall cause those characters
to be sent to the recipient's terminal.'' [Ibid., p. 694,
lines 5982-5983]
If {POSIX2_LOCALEDEF} is defined, a malicious user could
create a locale in which every character is printable. In
this case, a control sequence causing a line to be sent to
the system and then executed can be sent to an unsuspecting
user's terminal.
This is a security hole. Could lines 5996-5997:
``[h]owever, a user's privilege may further constrain the
domain of accessibility of other users' terminals'' [Ibid.,
p.694, lines 5996-5997] be used to close this hole, by
disallowing mortals from writing to other users' terminals
if their LC_CTYPE is not a public locale?
WG15 response for 9945-2:1993
-----------------------------------
The standard allows the behavior described in the interpretation
request. Concern over this has been forwarded to the sponsors of the
standard.
Rationale for Interpretation:
-----------------------------
None.
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