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Excessive resource use in malformed ssh traffic parsing

High
victorjulien published GHSA-mhhx-xw7r-r5c8 Apr 2, 2024

Package

suricata

Affected versions

<=6.0.16
>= 7.0.0, <= 7.0.3

Patched versions

6.0.17
7.0.4

Description

Impact

When parsing an overly long SSH banner, Suricata can use excessive CPU resources, as well as cause excessive logging volume in alert records.

Patches

Upgrade to 7.0.4 or 6.0.17.

Workarounds

There are several possible workarounds.

Use a rule to bypass the flow when an overly long SSH banner arrives like :
alert ssh any any -> any any (msg:"SURICATA SSH too long banner"; flow:established; app-layer-event:ssh.long_banner; classtype:protocol-command-decode; sid:2228001; rev:2; bypass;)

Alternatively, there are several things that help avoid or reduce the issue:

  • disable ssh parser (avoid)
  • set a low stream.reassembly.depth value (reduce)
  • disable EVE ssh logging (reduce)

References

https://redmine.openinfosecfoundation.org/issues/6800 (6.0.x)
https://redmine.openinfosecfoundation.org/issues/6801 (7.0.x)

Credits

Found using quadfuzz on Oss-Fuzz.

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVE ID

CVE-2024-28870

Weaknesses