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securityvulnsSecurityvulnsSECURITYVULNS:DOC:30922
HistoryJul 14, 2014 - 12:00 a.m.

[oss-security] CVE request: python: _json module is vulnerable to arbitrary process memory read

2014-07-1400:00:00
vulners.com
30

Hello,

It was reported [1] that Python built-in _json module have a flaw
(insufficient bounds checking), which allows a local user to read
current process' arbitrary memory.
From initial bug report [1]:

The sole prerequisites of this attack are that the attacker is able to
control or influence the two parameters of the default scanstring
function: the string to be decoded and the index.

The bug is caused by allowing the user to supply a negative index
value. The index value is then used directly as an index to an array
in the C code; internally the address of the array and its index are
added to each other in order to yield the address of the value that is
desired. However, by supplying a negative index value and adding this
to the address of the array, the processor's register value wraps
around and the calculated value will point to a position in memory
which isn't within the bounds of the supplied string, causing the
function to access other parts of the process memory.

Can a CVE ID be assigned to this issue please?
Also CC'ing the Debian bugreport here.

References:
[1] Upstream bug report with additional technical details: http://bugs.python.org/issue21529
[2] Debian bug tracker: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=752395
[3] RedHat bug tracker: https://bugzilla.redhat.com/show_bug.cgi?id=1112285

Thanks.
– Vasyl Kaigorodov | Red Hat Product Security Team PGP: 0xABB6E828 A7E0 87FF 5AB5 48EB 47D0 2868 217B F9FC ABB6 E828