Race Condition Enabling Link Following

Opis

The product checks the status of a file or directory before accessing it, which produces a race condition in which the file can be replaced with a link before the access is performed, causing the product to access the wrong file.

While developers might expect that there is a very narrow time window between the time of check and time of use, there is still a race condition. An attacker could cause the product to slow down (e.g. with memory consumption), causing the time window to become larger. Alternately, in some situations, the attacker could win the race by performing a large number of attacks.

Skutki

• Confidentiality, Integrity

  Read Files or Directories; Modify Files or Directories

Słabość nadrzędna

• CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

Może prowadzić do

• CWE-59 Improper Link Resolution Before File Access ('Link Following')

Kiedy powstaje

• Architecture and Design
• Implementation

Dotyczy

Not Language-Specific

Uwagi

This is already covered by the "Link Following" weakness (CWE-59). It is included here because so many people associate race conditions with link problems; however, not all link following issues involve race conditions.

Źródła

1. The Art of Software Security Assessment — Mark Dowd, John McDonald, Justin Schuh, Chapter 9, "Race Conditions", Page 526, Addison Wesley, 2006