module

glibc LD_AUDIT Arbitrary DSO Load Privilege Escalation

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Disclosed
10/18/2010
Created
06/14/2018

Description

This module attempts to gain root privileges on Linux systems by abusing
a vulnerability in the GNU C Library (glibc) dynamic linker.

glibc ld.so in versions before 2.11.3, and 2.12.x before 2.12.2 does not
properly restrict use of the LD_AUDIT environment variable when loading
setuid executables. This allows loading arbitrary shared objects from
the trusted library search path with the privileges of the suid user.

This module uses LD_AUDIT to load the libpcprofile.so shared object,
distributed with some versions of glibc, and leverages arbitrary file
creation functionality in the library constructor to write a root-owned
world-writable file to a system trusted search path (usually /lib).
The file is then overwritten with a shared object then loaded with
LD_AUDIT resulting in arbitrary code execution.

This module has been tested successfully on glibc version 2.11.1 on
Ubuntu 10.04 x86_64 and version 2.7 on Debian 5.0.4 i386.

RHEL 5 is reportedly affected, but untested. Some glibc distributions
do not contain the libpcprofile.so library required for successful
exploitation.

Authors

Tavis Ormandyzx2c4Marco IvaldiTodor Donevbcoles

Platform

Linux

Architectures

x86, x64

References

Module Options

To display the available options, load the module within the Metasploit console and run the commands ‘show options’ or ‘show advanced’:

    msf > use exploit/linux/local/glibc_ld_audit_dso_load_priv_esc
    msf /(c) > show actions
        ...actions...
    msf /(c) > set ACTION < action-name >
    msf /(c) > show options
        ...show and set options...
    msf /(c) > run
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