Security Bulletin: Vulnerabilities in Curl affect PowerSC (CVE-2021-22876 and CVE-2021-22890)

Summary

There are vulnerabilities in Curl that affect PowerSC.

Vulnerability Details

CVEID:CVE-2021-22876
**DESCRIPTION:**cURL libcurl could allow a remote attacker to obtain sensitive information, caused by the failure to strip off user credentials from the URL when automatically populating the Referer: HTTP request header field in outgoing HTTP requests. By sending a specially-crafted HTTP request, an attacker could exploit this vulnerability to obtain user credentials, and use this information to launch further attacks against the affected system.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/199186 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)

CVEID:CVE-2021-22890
**DESCRIPTION:**cURL libcurl is vulnerable to a man-in-the-middle attack, caused by a session tickets confusing issue when using a HTTPS proxy and TLS 1.3. An attacker could exploit this vulnerability to launch a man-in-the-middle attack and gain access to the communication channel between endpoints to obtain sensitive information or further compromise the system.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/199188 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)

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_fix6.tar

<http://aix.software.ibm.com/aix/efixes/powersc/security/curl_fix6.tar&gt;

<https://aix.software.ibm.com/aix/efixes/powersc/security/curl_fix6.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_fix6.tar
cd curl_fix6

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
—|—

95ae1e55a1bd3d6311bd20363c3b596003391dd2902b99c4e58fa40226c3d0af

|

curl-7.76.1-1.aix6.1.ppc.rpm

08ddc62bc54d7e7ac7e7cd5b1f79dddca7c559f0b7c8c63a7685404236a264ca

|

ca-certificates-2020.06.01-2.aix6.1.ppc.rpm

f79ef9e87fadb23574ce4da53aa79bdf45668e138d9da3975ff22aef511c265e

|

krb5-libs-1.18.3-1.aix6.1.ppc.rpm

5c107b7919f89bfc9f76dd2bd4fe15e650c8ed303010ea094b1f799bfdae605c

|

openldap-2.4.58-1.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_advisory6.asc.sig&gt;

<https://aix.software.ibm.com/aix/efixes/powersc/security/curl_advisory6.asc.sig&gt;

ftp://aix.software.ibm.com/aix/efixes/powersc/security/curl_advisory6.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_fix6.tar
cd curl_fix6

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