OpenBSD up to 6.6 setuid Program ld.so _dl_setup_env LD_LIBRARY_PATH privileges management

Summaryinfo

A vulnerability was found in OpenBSD up to 6.6. It has been rated as critical. This impacts the function _dl_setup_env of the file ld.so of the component setuid Program Handler. The manipulation of the argument LD_LIBRARY_PATH leads to privileges management. This vulnerability is referenced as CVE-2019-19726. The attack can only be performed from a local environment. Furthermore, an exploit is available.

Detailsinfo

A vulnerability, which was classified as critical, has been found in OpenBSD up to 6.6 (Operating System). This issue affects the function _dl_setup_env of the file ld.so of the component setuid Program Handler. The manipulation of the argument LD_LIBRARY_PATH with an unknown input leads to a privileges management vulnerability. Using CWE to declare the problem leads to CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

OpenBSD through 6.6 allows local users to escalate to root because a check for LD_LIBRARY_PATH in setuid programs can be defeated by setting a very small RLIMIT_DATA resource limit. When executing chpass or passwd (which are setuid root), _dl_setup_env in ld.so tries to strip LD_LIBRARY_PATH from the environment, but fails when it cannot allocate memory. Thus, the attacker is able to execute their own library code as root.

The weakness was published 12/12/2019 (Website). It is possible to read the advisory at openbsd.org. The identification of this vulnerability is CVE-2019-19726 since 12/11/2019. Attacking locally is a requirement. The successful exploitation requires a simple authentication. Technical details as well as a public exploit are known. The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

A public exploit has been developed by Qualys Corporation in C and been published 4 days after the advisory. The exploit is available at exploit-db.com. It is declared as proof-of-concept.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Exploit-DB (47780). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Operating System

Name

• OpenBSD

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6

License

• open-source

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CPE 2.2info

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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