Amazon Linux AMI update for tigervnc

Published: 2020-12-19

Risk	High
Patch available	YES
Number of vulnerabilities	5
CVE-ID	CVE-2019-15691 CVE-2019-15692 CVE-2019-15693 CVE-2019-15694 CVE-2019-15695
CWE-ID	CWE-672 CWE-787 CWE-122
Exploitation vector	Network
Public exploit	N/A
Vulnerable software Subscribe	Amazon Linux AMI Operating systems & Components / Operating system
Vendor	Amazon Web Services

Security Bulletin

This security bulletin contains information about 5 vulnerabilities.

1) Use-after-return

EUVDB-ID: #VU23905

Risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-15691

CWE-ID: CWE-672 - Operation on a Resource after Expiration or Release

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to incorrect usage of stack memory in ZRLEDecoder. If decoding routine would throw an exception, ZRLEDecoder may try to access stack variable, which has been already freed during the process of stack unwinding. A remote attacker can execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Update the affected packages:

i686:
    tigervnc-debuginfo-1.8.0-21.34.amzn1.i686
    tigervnc-1.8.0-21.34.amzn1.i686
    tigervnc-server-module-1.8.0-21.34.amzn1.i686
    tigervnc-server-1.8.0-21.34.amzn1.i686

src:
    tigervnc-1.8.0-21.34.amzn1.src

x86_64:
    tigervnc-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-module-1.8.0-21.34.amzn1.x86_64
    tigervnc-debuginfo-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-1.8.0-21.34.amzn1.x86_64

Vulnerable software versions

Amazon Linux AMI: All versions

CPE2.3

cpe:2.3:o:amazon_web_services:amazon_linux_ami:*:*:*:*:*:*:*:

External links

http://alas.aws.amazon.com/ALAS-2020-1470.html

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Out-of-bounds write

EUVDB-ID: #VU23906

Risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-15692

CWE-ID: CWE-787 - Out-of-bounds write

Exploit availability: No

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to incorrect value checks. A remote attacker can trigger out-of-bounds write from "CopyRectDecoder" and execute arbitrary code on the target system.

Mitigation

Update the affected packages:

i686:
    tigervnc-debuginfo-1.8.0-21.34.amzn1.i686
    tigervnc-1.8.0-21.34.amzn1.i686
    tigervnc-server-module-1.8.0-21.34.amzn1.i686
    tigervnc-server-1.8.0-21.34.amzn1.i686

src:
    tigervnc-1.8.0-21.34.amzn1.src

x86_64:
    tigervnc-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-module-1.8.0-21.34.amzn1.x86_64
    tigervnc-debuginfo-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-1.8.0-21.34.amzn1.x86_64

Vulnerable software versions

Amazon Linux AMI: All versions

CPE2.3

cpe:2.3:o:amazon_web_services:amazon_linux_ami:*:*:*:*:*:*:*:

External links

http://alas.aws.amazon.com/ALAS-2020-1470.html

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

3) Heap-based buffer overflow

EUVDB-ID: #VU23907

Risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-15693

CWE-ID: CWE-122 - Heap-based Buffer Overflow

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in "TightDecoder::FilterGradient". A remote attacker can trigger heap-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Update the affected packages:

i686:
    tigervnc-debuginfo-1.8.0-21.34.amzn1.i686
    tigervnc-1.8.0-21.34.amzn1.i686
    tigervnc-server-module-1.8.0-21.34.amzn1.i686
    tigervnc-server-1.8.0-21.34.amzn1.i686

src:
    tigervnc-1.8.0-21.34.amzn1.src

x86_64:
    tigervnc-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-module-1.8.0-21.34.amzn1.x86_64
    tigervnc-debuginfo-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-1.8.0-21.34.amzn1.x86_64

Vulnerable software versions

Amazon Linux AMI: All versions

CPE2.3

cpe:2.3:o:amazon_web_services:amazon_linux_ami:*:*:*:*:*:*:*:

External links

http://alas.aws.amazon.com/ALAS-2020-1470.html

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

4) Heap-based buffer overflow

EUVDB-ID: #VU23903

Risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-15694

CWE-ID: CWE-122 - Heap-based Buffer Overflow

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to the signedness error in processing MemOutStream. A remote attacker can trigger heap-based buffer overflow from DecodeManager::decodeRect and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Update the affected packages:

i686:
    tigervnc-debuginfo-1.8.0-21.34.amzn1.i686
    tigervnc-1.8.0-21.34.amzn1.i686
    tigervnc-server-module-1.8.0-21.34.amzn1.i686
    tigervnc-server-1.8.0-21.34.amzn1.i686

src:
    tigervnc-1.8.0-21.34.amzn1.src

x86_64:
    tigervnc-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-module-1.8.0-21.34.amzn1.x86_64
    tigervnc-debuginfo-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-1.8.0-21.34.amzn1.x86_64

Vulnerable software versions

Amazon Linux AMI: All versions

CPE2.3

cpe:2.3:o:amazon_web_services:amazon_linux_ami:*:*:*:*:*:*:*:

External links

http://alas.aws.amazon.com/ALAS-2020-1470.html

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

5) Out-of-bounds write

EUVDB-ID: #VU23908

Risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-15695

CWE-ID: CWE-787 - Out-of-bounds write

Exploit availability: No

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to insufficient sanitization of PixelFormat. A remote attacker can trigger out-of-bounds write from "CMsgReader::readSetCursor" and execute arbitrary code on the target system.

Mitigation

Update the affected packages:

i686:
    tigervnc-debuginfo-1.8.0-21.34.amzn1.i686
    tigervnc-1.8.0-21.34.amzn1.i686
    tigervnc-server-module-1.8.0-21.34.amzn1.i686
    tigervnc-server-1.8.0-21.34.amzn1.i686

src:
    tigervnc-1.8.0-21.34.amzn1.src

x86_64:
    tigervnc-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-module-1.8.0-21.34.amzn1.x86_64
    tigervnc-debuginfo-1.8.0-21.34.amzn1.x86_64
    tigervnc-server-1.8.0-21.34.amzn1.x86_64

Vulnerable software versions

Amazon Linux AMI: All versions

CPE2.3

cpe:2.3:o:amazon_web_services:amazon_linux_ami:*:*:*:*:*:*:*:

External links

http://alas.aws.amazon.com/ALAS-2020-1470.html

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.