Security Bulletin: Due to RPM, AIX is vulnerable to arbitrary code execution (CVE-2021-20271), RPM database corruption (CVE-2021-3421), and denial of service (CVE-2021-20266)

Summary

AIX is vulnerable to arbitrary code execution (CVE-2021-20271), RPM database corruption (CVE-2021-3421), and denial of service (CVE-2021-20266) due to RPM. RPM is used by AIX for package management.

Vulnerability Details

CVEID:CVE-2021-20271
**DESCRIPTION:**RPM could allow a remote attacker to execute arbitrary code on the system, caused by a flaw in the signature check function. By persuading a victim to open a specially-crafted package file, an attacker could exploit this vulnerability to cause RPM database corruption and execute arbitrary code on the system.
CVSS Base score: 6.7
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/198961 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H)

CVEID:CVE-2021-3421
**DESCRIPTION:**RPM Project RPM could allow a remote attacker to bypass security restrictions, caused by a flaw in the read function. By persuading a victim to install a seemingly verifiable package or compromise an RPM repository, an attacker could exploit this vulnerability to cause a corruption to the RPM database.
CVSS Base score: 6.1
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/203124 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L)

CVEID:CVE-2021-20266
**DESCRIPTION:**RPM Project RPM is vulnerable to a denial of service, caused by an out-of-bounds read flaw in the hdrblobInit function in lib/header.c. By sending a specially-crafted request, a local authenticated attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base score: 3.1
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/201041 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L)

Affected Products and Versions

The following fileset levels are vulnerable:

To find out whether the affected filesets are installed on your systems, refer to the lslpp command found in AIX user’s guide.

Example: lslpp -L | grep -i rpm.rte

Remediation/Fixes

A. FIXES

IBM strongly recommends addressing the vulnerability now.

AIX and VIOS fixes are available.

The AIX and VIOS fixes can be downloaded via ftp or http from:

ftp://aix.software.ibm.com/aix/efixes/security/rpm_fix.tar

<http://aix.software.ibm.com/aix/efixes/security/rpm_fix.tar&gt;

<https://aix.software.ibm.com/aix/efixes/security/rpm_fix.tar&gt;

The link above is to a tar file containing this signed advisory, fix packages, and OpenSSL signatures for each package. The fixes below include prerequisite checking. This will enforce the correct mapping between the fixes and AIX Technology Levels.

To extract the fixes from the tar file:

tar xvf rpm_fix.tar

cd rpm_fix

Verify you have retrieved the fixes intact:

The checksums below were generated using the “openssl dgst -sha256 [filename]” command as the following:

These sums should match exactly. The OpenSSL signatures in the tar file and on this advisory can also be used to verify the integrity of the fixes. If the sums or signatures cannot be confirmed, contact IBM Support at <http://ibm.com/support/&gt; and describe the discrepancy.

openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]

openssl dgst -sha256 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file]

Published advisory OpenSSL signature file location:

<http://aix.software.ibm.com/aix/efixes/security/rpm_advisory.asc.sig&gt;

<https://aix.software.ibm.com/aix/efixes/security/rpm_advisory.asc.sig&gt;

ftp://aix.software.ibm.com/aix/efixes/security/rpm_advisory.asc.sig

B. FIX INSTALLATION

If possible, it is recommended that a mksysb backup of the system be created. Verify it is both bootable and readable before proceeding.

To preview the fix installation:

For AIX 7.1 and 7.2:

installp -apYd . rpm.rte 4.15.1.1006

For AIX 7.3:

installp -apYd . rpm.rte 4.15.1.2006

To install the fix package:

For AIX 7.1 and 7.2:

installp -aXYd . rpm.rte 4.15.1.1006

For AIX 7.3:

installp -aXYd . rpm.rte 4.15.1.2006

Workarounds and Mitigations

None