module

glibc LD_AUDIT Arbitrary DSO Load Privilege Escalation

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Disclosed
Oct 18, 2010
Created
Jun 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 Ormandy
zx2c4
Marco Ivaldi
Todor Donev
bcoles [email protected]

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 exploit(glibc_ld_audit_dso_load_priv_esc) > show targets
        ...targets...
    msf exploit(glibc_ld_audit_dso_load_priv_esc) > set TARGET < target-id >
    msf exploit(glibc_ld_audit_dso_load_priv_esc) > show options
        ...show and set options...
    msf exploit(glibc_ld_audit_dso_load_priv_esc) > exploit
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