TITLE:
Perl Explicit Format Parameter Index Integer Overflow Vulnerability

SECUNIA ADVISORY ID:
SA17802

VERIFY ADVISORY:
http://secunia.com/advisories/17802/

CRITICAL:
Not critical

IMPACT:
DoS

WHERE:
>From remote

SOFTWARE:
Perl 5.x
http://secunia.com/product/2647/

DESCRIPTION:
Jack Louis has discovered a vulnerability in Perl, which can be
exploited by malicious people to cause a Denial of Service.

The vulnerability is caused due to an integer overflow error in the
"Perl_sv_vcatpvfn()" function of "sv.c" when handing a format string
that contains an explicit format parameter index that exceeds
INT_MAX. This can exploited to cause illegal memory access which
causes an affected Perl application to crash. 

Example:
perl -e 'printf("%2147483649\$n");'

The vulnerability has been confirmed in version 5.8.7 and also
reported in versions 5.8.6  and 5.9.2. Other versions may also be
affected.

Note: This vulnerability must be exploited in conjunction with a
format string vulnerability in a Perl application. Exploiting this
vulnerability for arbitrary code execution has not been confirmed.

SOLUTION:
Ensure that Perl applications do not use unsanitised input as format
string.

PROVIDED AND/OR DISCOVERED BY:
Jack Louis, Dyad Security.

ORIGINAL ADVISORY:
http://www.dyadsecurity.com/perl-0002.html

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