Observable Timing Discrepancy

Opis

Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.

In security-relevant contexts, even small variations in timing can be exploited by attackers to indirectly infer certain details about the product's internal operations. For example, in some cryptographic algorithms, attackers can use timing differences to infer certain properties about a private key, making the key easier to guess. Timing discrepancies effectively form a timing side channel.

Skutki

• Confidentiality, Access Control

  Read Application Data; Bypass Protection Mechanism

Przykłady podatności

• CVE-2019-10071 Java-oriented framework compares HMAC signatures using String.equals() instead of a constant-time algorithm, causing timing discrepancies
• CVE-2019-10482 Smartphone OS uses comparison functions that are not in constant time, allowing side channels
• CVE-2014-0984 Password-checking function in router terminates validation of a password entry when it encounters the first incorrect character, which allows remote attackers to obtain passwords via a brute-force attack that relies on timing differences in responses to incorrect password guesses, aka a timing side-channel attack.
• CVE-2003-0078 SSL implementation does not perform a MAC computation if an incorrect block cipher padding is used, which causes an information leak (timing discrepancy) that may make it easier to launch cryptographic attacks that rely on distinguishing between padding and MAC verification errors, possibly leading to extraction of the original plaintext, aka the "Vaudenay timing attack."
• CVE-2000-1117 Virtual machine allows malicious web site operators to determine the existence of files on the client by measuring delays in the execution of the getSystemResource method.
• CVE-2003-0637 Product uses a shorter timeout for a non-existent user than a valid user, which makes it easier for remote attackers to guess usernames and conduct brute force password guessing.
• CVE-2003-0190 Product immediately sends an error message when a user does not exist, which allows remote attackers to determine valid usernames via a timing attack.
• CVE-2004-1602 FTP server responds in a different amount of time when a given username exists, which allows remote attackers to identify valid usernames by timing the server response.
• CVE-2005-0918 Browser allows remote attackers to determine the existence of arbitrary files by setting the src property to the target filename and using Javascript to determine if the web page immediately stops loading, which indicates whether the file exists or not.

Słabość nadrzędna

• CWE-203 Observable Discrepancy

Może prowadzić do

• CWE-385 Covert Timing Channel
• CWE-327 Use of a Broken or Risky Cryptographic Algorithm

Słabości podrzędne

• CWE-1254 Incorrect Comparison Logic Granularity

Kiedy powstaje

• Architecture and Design — COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
• Implementation
• Operation

Dotyczy

Not Language-Specific, Not Technology-Specific

Uwagi

Often primary in cryptographic applications and algorithms.

CWE 4.16 removed a demonstrative example for a hardware module because it was inaccurate and unable to be adapted. The CWE team is developing an alternative.