MirBSD Korn Shell TTY privilege escalation

mirbsd-tty-privilege-escalation (41794)

High Risk

Description:

MirBSD Korn Shell could allow a local attacker to gain elevated privileges on the system, caused by an error during a TTY attachment. By using characters previously assigned to the attached virtual console to attach to a TTY, a local attacker could exploit this vulnerability to execute arbitrary commands on the system with the privileges of the victim running mksh.

*CVSS:

Base Score:	4.6
Access Vector:	Local
Access Complexity:	Low
Authentication:	None
Confidentiality Impact:	Partial
Integrity Impact:	Partial
Availability Impact:	Partial
Temporal Score:	3.4
Exploitability:	Unproven
Remediation Level:	Official-Fix
Report Confidence:	Confirmed

Consequences:

Gain Privileges

Remedy:

Upgrade to the latest version of MirBSD Korn Shell (R33d or later), available from the MirBSD Web site. See References.

References:

• MirBSD Web site: Recent Changes, mksh R33d.
• BID-28768: MirBSD Korn Shell Local Privilege Escalation Vulnerability
• CVE-2008-1845: The Korn shell (aka mksh) before R33d on MirOS (aka MirBSD) does not flush the tty's I/O when invoking mksh in a new terminal, which allows local users to gain privileges by opening a virtual terminal and entering command sequences, which might later be executed in opportunistic circumstances by a different user who launches mksh and specifies that terminal with the -T option.
• SA29803: MirBSD Korn Shell TTY Attachment Privilege Escalation

Platforms Affected:

• MirOS MirBSD Korn Shell prior to R33d

Reported:

Apr 14, 2008

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