Brute-force bypass via login-response timing side channel
Published May 17, 2021 · Updated Aug 3, 2024
Authentication protection bypass in D-Link DIR-842E firmware 3.0.2 and earlier allows remote attackers to accelerate Telnet password guessing. The telnetd login path delays invalid-password responses by three seconds but sends “Welcome” immediately for valid credentials, creating a timing oracle. LAN access to TCP port 23 is required; the flaw removes the enforced pause between guesses but does not independently disclose or alter credentials.
Summary
What happened
Authentication protection bypass in D-Link DIR-842E firmware 3.0.2 and earlier allows remote attackers to accelerate Telnet password guessing. The telnetd login path delays invalid-password responses by three seconds but sends “Welcome” immediately for valid credentials, creating a timing oracle. LAN access to TCP port 23 is required; the flaw removes the enforced pause between guesses but does not independently disclose or alter credentials.
The record
- CVE
- CVE-2021-27342
- Published
- May 17, 2021
- Updated
- Aug 3, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-203, T1110.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 17, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- D-Link-CVE-2021-27342-exploitfunctional · unverified
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Technologies
Your stack
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Your stack
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