Security Bulletin: Vulnerabilities in Curl affect PowerSC (CVE-2020-8284, CVE-2020-8285, and CVE-2020-8286)

Summary

There are a vulnerabilities in Curl that affect PowerSC.

Vulnerability Details

CVEID:CVE-2020-8284
**DESCRIPTION:**cURL libcurl could allow a remote attacker to obtain sensitive information, caused by improper validation of FTP PASV responses. By persuading a victim to connect a specially-crafted server, an attacker could exploit this vulnerability to obtain sensitive information about services, and use this information to launch further attacks against the affected system.
CVSS Base score: 6.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/192854 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N)

CVEID:CVE-2020-8286
**DESCRIPTION:**cURL libcurl could allow a remote attacker to bypass security restrictions, caused by improper OCSP response verification. By sending a specially-crafted request, an attacker could exploit this vulnerability to breach a TLS server.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/192856 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N)

CVEID:CVE-2020-8285
**DESCRIPTION:**cURL libcurl is vulnerable to a denial of service, caused by a stack-based buffer overflow in the wildcard matching function. By sending a specially-crafted request, a remote attacker could exploit this vulnerability to cause the application to crash.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/192855 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Affected Products and Versions

The vulnerabilities in the following filesets are being addressed:

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

Example: lslpp -l | grep powerscStd

Example: rpm -qa | grep curl

Remediation/Fixes

A. FIXES

Fixes are available.

The fixes can be downloaded via ftp or http from:

ftp://aix.software.ibm.com/aix/efixes/powersc/security/curl_fix5.tar

<http://aix.software.ibm.com/aix/efixes/powersc/security/curl_fix5.tar&gt;

<https://aix.software.ibm.com/aix/efixes/powersc/security/curl_fix5.tar&gt;

The link above is to a tar file containing this signed advisory, open source fix packages, and OpenSSL signatures for each package.

To extract the fixes from the tar file:
tar xvf curl_fix5.tar
cd curl_fix5

Verify you have retrieved the fixes intact:

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

openssl dgst -sha256

| filename
—|—

f6e675a84b83b5975c644cc6b78d7ff8373741a7de4c9240e0130c15299b2e9e

|

ca-certificates-2019.01.10-2.aix6.1.ppc.rpm

5d42090b8be3c1e2258d129ee1231815cfb6650b9496c97d4f3acffd9bcc29e0

|

curl-7.74.0-1.aix6.1.ppc.rpm

210a76ea9216beb34df0e3c510f48c7c8a4044ad608980c26cb8b2d9d0fe8724

|

p11-kit-0.23.16-1.aix6.1.ppc.rpm

47f88f4f6c1ec31b3d85da88430df970f7937a6b90f1a602fabf9addbb4e18a5

|

p11-kit-tools-0.23.16-1.aix6.1.ppc.rpm

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.

openssl dgst -sha1 -verify <pubkey_file> -signature <advisory_file>.sig <advisory_file>
openssl dgst -sha1 -verify <pubkey_file> -signature <ifix_file>.sig <ifix_file>

Published advisory OpenSSL signature file location:

<http://aix.software.ibm.com/aix/efixes/powersc/security/curl_advisory5.asc.sig&gt;

<https://aix.software.ibm.com/aix/efixes/powersc/security/curl_advisory5.asc.sig&gt;

ftp://aix.software.ibm.com/aix/efixes/powersc/security/curl_advisory5.asc.sig

B. FIX AND INTERIM FIX INSTALLATION

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

To extract the fixes from the tar file:
tar xvf curl_fix5.tar
cd curl_fix5

To install a fix package:
rpm -ivh *.rpm
rpm -Uvh *.rpm

Interim fixes have had limited functional and regression testing but not the full regression testing that takes place for Service Packs; however, IBM does fully support them.

Workarounds and Mitigations

None