SEI CERT Oracle Coding Standard for Java

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Comment: replaced reference from voided FIO00 with some stuff from that rule

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  • A TOCTOU race condition exists between the first check and open. During this race window, an attacker can replace the regular file with a symbolic link or other non-regular file. The second check detects this race condition but does not eliminate it; an attacker can still cause the system to block when opening the file.
  • An attacker could subvert this code by letting the check operate on a normal file, substituting the non-normal file for the open, and then resubstitute the normal file to circumvent the second check. This vulnerability exists because Java lacks any mechanism to obtain file attributes from a file by any means other than the file name, and the binding of the file name to a file object is reasserted every time the file name is used in an operation. Consequently, an attacker can still switch out a file for a nefarious file, such as a symbolic link.
  • A system with hard links allows an attacker to construct a malicious file that is a hard link to a sensitive file. Hard links cannot be reliably detected by a program, and serve as a foil to canonicalization attempts which are prescribed by IDS03 IDS02-J. Canonicalize path names before validating them.

Compliant Solution (POSIX, Java 1.7, secure directory)

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[[API 2006

AA. Bibliography#API 06]]

Class File, methods createTempFile, delete, deleteOnExit

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[[CVE 2008

AA. Bibliography#CVE 08]]

[CVE-2008-5354

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-5354]

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[[Darwin 2004

AA. Bibliography#Darwin 04]]

11.5 Creating a Transient File

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[[Garfinkel 1996

AA. Bibliography#Garfinkel 96]]

Section 5.6, "Device Files"

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[[Howard 2002

AA. Bibliography#Howard 02]]

Chapter 11, "Canonical Representation Issues"

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[[J2SE 2011

AA. Bibliography#J2SE 11]]

The try-with-resources Statement

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[[Open Group 2004

AA. Bibliography#Open Group 04]]

[open()

http://www.opengroup.org/onlinepubs/009695399/functions/open.html]

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[[SDN 2008

AA. Bibliography#SDN 08]]

Bug IDs: 4171239, 4405521, 4635827, 4631820

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[[Secunia 2008

AA. Bibliography#Secunia 08]]

[Secunia Advisory 20132

http://secunia.com/advisories/20132/]

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