Improper Check for Dropped Privileges Affecting bash Open this link in a new tab package, versions <4.3-14ubuntu1.4+esm1


low
  • Exploit Maturity

    Mature

  • Attack Complexity

    Low

  • Confidentiality

    High

  • Integrity

    High

  • Availability

    High

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  • snyk-id

    SNYK-UBUNTU1604-BASH-542609

  • published

    28 Nov 2019

  • disclosed

    28 Nov 2019

How to fix?

Upgrade Ubuntu:16.04 bash to version 4.3-14ubuntu1.4+esm1 or higher.

NVD Description

Note: Versions mentioned in the description apply to the upstream bash package. See How to fix? for Ubuntu:16.04 relevant versions.

An issue was discovered in disable_priv_mode in shell.c in GNU Bash through 5.0 patch 11. By default, if Bash is run with its effective UID not equal to its real UID, it will drop privileges by setting its effective UID to its real UID. However, it does so incorrectly. On Linux and other systems that support "saved UID" functionality, the saved UID is not dropped. An attacker with command execution in the shell can use "enable -f" for runtime loading of a new builtin, which can be a shared object that calls setuid() and therefore regains privileges. However, binaries running with an effective UID of 0 are unaffected.