Patchfirst
CVE-2020-8617 Public exploit High · 7.5 EPSS 93.3%

A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c

ISC · BIND9

Summary

A logic error in BIND9 (ISC's DNS server), in the code that checks TSIG validity in tsig.c, can be triggered to cause an assertion failure. An attacker who sends a specially crafted message over the network, without authentication or user interaction, can do so if they know or successfully guess the name of a TSIG key used by the server, which is commonly the default local session key present on most BIND servers.

Official description · CVE.org

Using a specially-crafted message, an attacker may potentially cause a BIND server to reach an inconsistent state if the attacker knows (or successfully guesses) the name of a TSIG key used by the server. Since BIND, by default, configures a local session key even on servers whose configuration does not otherwise make use of it, almost all current BIND servers are vulnerable. In releases of BIND dating from March 2018 and after, an assertion check in tsig.c detects this inconsistent state and deliberately exits. Prior to the introduction of the check the server would continue operating in an inconsistent state, with potentially harmful results.

Breakdown
30.9 / 100
Exploited
Not confirmed
Reports
0
Tactics
0/15

Public exploit code (Metasploit) was available the same day.

  1. DisclosedPublic exploit codeMetasploitday 0

techniques

No techniques linked

No ATT&CK techniques are linked to this CVE yet. MITRE CTID has not mapped it, and no report passage in the corpus ties it to a technique.

What security researchers reported

Not named in any threat report yet

Also mentioned in 1 community threat pulse (AlienVault OTX)

Weaker evidence

Pulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.

References

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