Episode 210

Ubuntu Security Podcast

محتوای ارائه شده توسط Alex Murray and Ubuntu Security Team. تمام محتوای پادکست شامل قسمت‌ها، گرافیک‌ها و توضیحات پادکست مستقیماً توسط Alex Murray and Ubuntu Security Team یا شریک پلتفرم پادکست آن‌ها آپلود و ارائه می‌شوند. اگر فکر می‌کنید شخصی بدون اجازه شما از اثر دارای حق نسخه‌برداری شما استفاده می‌کند، می‌توانید روندی که در اینجا شرح داده شده است را دنبال کنید.https://fa.player.fm/legal

3M ago 21:20

MP3•خانه قسمت

Overview

It’s the Linux Security Summit in Bilbao this week and we bring you some highlights from our favourite talks, plus we cover the 25 most stubborn software weaknesses, and we look at security updates for Open VM Tools, libwebp, Django, binutils, Indent, the Linux kernel and more.

This week in Ubuntu Security Updates

88 unique CVEs addressed

[USN-6365-1] Open VM Tools vulnerability (00:45)

1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Lunar (23.04)
- CVE-2023-20900
Failed to properly validate SAML tokens - uses the xmlsec library but when verifying the signature on a SAML document, failed to configure the library to only use the X509 certificate for validation - since presumably an attacker could intercept the SAML token, and replace the X509 cert with a different type of signature which would then be trusted by the xmlsec library and allow the attacker to gain access

[USN-6366-1] PostgreSQL vulnerability (01:34)

1 CVEs addressed in Xenial ESM (16.04 ESM)
- CVE-2023-39417
Fixed for other releases in [USN-6296-1] PostgreSQL vulnerabilities in Episode 206 - one issue, which allowed an attacker to escalate their privileges (from CREATE to being able to execute arbitrary code as a bootstrap superuser) also affected PostgreSQL 9.5 in Ubuntu 16.04

[USN-6364-1] Ghostscript vulnerabilities (01:59)

2 CVEs addressed in Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM), Focal (20.04 LTS)
- CVE-2020-21890
- CVE-2020-21710
Divide by zero and buffer overflow in handling of PDFs -> DoS / RCE?

[USN-6369-1] libwebp vulnerability (02:19)

1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Lunar (23.04)
- CVE-2023-4863
heap buffer overflow -> OOB write -> RCE
originally reported as a vuln in Chrome on 12 September - full impact that this was actually a bug in libwebp became clear a few days later
- Solar Designer has a good thread on the details on oss-security

[USN-6367-1] Firefox vulnerability (03:55)

1 CVEs addressed in Focal (20.04 LTS)
- CVE-2023-4863
117.0.1 for the libwebp fix above

[USN-6368-1] Thunderbird vulnerabilities (04:04)

6 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Lunar (23.04)
102.15.1 - libwebp issue above plus various other issues - various UAFs, missing .xll files from standard blocklist that warns users when downloading executables - more of a windows issue but these are Excel add-in files - ie. plugins for Excel, “memory safety bugs”

[USN-6370-1] ModSecurity vulnerabilities (04:42)

3 CVEs addressed in Trusty ESM (14.04 ESM), Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM), Focal (20.04 LTS), Jammy (22.04 LTS)
CPU-based DoS when parsing excessively nested JSON objects (needs to be tens-of-thousands deep)
Mishandling of NUL byte in file uploads - would parse the filename as a string but if it contained an embedded NUL byte then filename would be truncated and hence could result in a buffer overread or the ability to bypass the web application firewall for rules which read from the FILES_TMP_CONTENT variable
Mishandling of HTTP multipart requests could also allow to bypass WAF

[USN-6371-1] libssh2 vulnerability (06:07)

1 CVEs addressed in Trusty ESM (14.04 ESM), Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM), Focal (20.04 LTS)
- CVE-2020-22218
OOB read - low impact since requires to connect to a malicious server to trigger - and outcome is likely a DoS

[USN-6372-1] DBus vulnerability (06:26)

1 CVEs addressed in Xenial ESM (16.04 ESM)
- CVE-2023-34969
Ability to crash the dbus daemon by an unprivileged user - BUT only if there is a privileged user using the in-built monitoring interface of dbus to monitor the traffic - so low chance of being able to trigger this and the outcome is just a DoS anyway - and will be restarted by systemd anyway

[USN-6373-1] gawk vulnerability (07:02)

1 CVEs addressed in Trusty ESM (14.04 ESM), Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM), Focal (20.04 LTS), Jammy (22.04 LTS)
- CVE-2023-4156
Heap OOB read - DoS

[USN-6374-1] Mutt vulnerabilities (07:16)

2 CVEs addressed in Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM), Focal (20.04 LTS), Jammy (22.04 LTS), Lunar (23.04)
- CVE-2023-4875
- CVE-2023-4874
2 different NULL ptr deref
- viewing crafted email
- composing from a specially crafted draft email
- DoS only

[USN-6375-1] atftp vulnerability (07:38)

Affecting Jammy (22.04 LTS), Lunar (23.04)
Could crash atftpd if requesting a non-existant file - turns out to be a buffer overflow so could possibly be used for code execution

[USN-6376-1] c-ares vulnerability (7:50)

1 CVEs addressed in Focal (20.04 LTS)
- CVE-2020-22217
OOB read when parsing a crafted Start of Authority (SOA) reply

[USN-6377-1] LibRaw vulnerability (7:56)

1 CVEs addressed in Focal (20.04 LTS)
- CVE-2020-22628
Failed to reject images with invalid pixel aspect ratio - leading to an OOB read -> crash

[USN-6378-1] Django vulnerability (08:08)

1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Lunar (23.04)
- CVE-2023-41164
DoS via handling of URIs with a very large number of unicode characters - algorithm would parse from start of string forwards for every invalid unicode character - instead of just using the remainder of the string

[USN-6379-1] vsftpd vulnerability (08:47)

1 CVEs addressed in Focal (20.04 LTS)
- CVE-2021-3618
Possible application layer confusion attack (ALPACA) - abuses wildcard or multi-domain certificates to redirect traffic from one subdomain to another

[USN-6381-1] GNU binutils vulnerabilities (09:07)

8 CVEs addressed in Trusty ESM (14.04 ESM), Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM)
memory leaks in nm and when disassembling microblaze instructions -> DoS
various buffer overflows in different functions -> DoS / RCE
failure to zero memory -> info leak
OOB read in objdump
heap buffer overflow in readelf
in general, we don’t consider it safe to run binutils on untrusted inputs

[USN-6380-1] Node.js vulnerabilities (09:54)

6 CVEs addressed in Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM), Focal (20.04 LTS)
abort when sending a crafted X509 certificate -> DoS
2 different HTTP request smuggling attacks
possible bypass of HTTP authorization since would include whitespace in HTTP headers
couple memory corruption issues in various operations implemented in C

[USN-6382-1] Memcached vulnerability (10:23)

1 CVEs addressed in Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM), Focal (20.04 LTS)
- CVE-2022-48571
NULL ptr deref upon reception of a UDP multi-packet request

[USN-6389-1] Indent vulnerability (10:30)

1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Lunar (23.04)
- CVE-2023-40305
heap buffer overflow -> DoS / RCE

[USN-6339-4] Linux kernel (Intel IoTG) vulnerabilities (10:53)

8 CVEs addressed in Jammy (22.04 LTS)
5.15
same set of vulns from [USN-6350-1, USN-6351-1, USN-6339-2, USN-6339-3] Linux kernel vulnerabilities

[USN-6383-1] Linux kernel vulnerabilities (11:15)

5 CVEs addressed in Jammy (22.04 LTS), Lunar (23.04)
6.2 all in 23.04, HWE in 22.04
speculative execution leak when performing a divide-by-zero on various AMD processors
possible privilege escalation in ARM64 KVM implementation -> guest VM could then write to host memory -> code execution
UAF in L2CAP socket handling in bluetooth - local DoS / code execution
UAF in various network packet classifiers - local DoS via unprivileged user namespace
Memory leak in netfilter - also able to be abused by an unprivileged user in a user namespace

[USN-6384-1] Linux kernel (OEM) vulnerabilities (12:23)

2 CVEs addressed in Jammy (22.04 LTS)
- CVE-2023-4569
- CVE-2023-20588
6.1
speculative execution leak when performing a divide-by-zero on various AMD processors
Memory leak in netfilter - also able to be abused by an unprivileged user in a user namespace

[USN-6385-1] Linux kernel (OEM) vulnerabilities (12:37)

37 CVEs addressed in Jammy (22.04 LTS)
6.0 OEM
All the previously mentioned vulns plus a heap more - kudos to OEM team and Timo Aaltonen from the kernel team for the most number of CVEs fixed this week

[USN-6386-1] Linux kernel vulnerabilities (13:01)

4 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS)
5.15 22.04 GA. 20.04 HWE

[USN-6387-1] Linux kernel vulnerabilities (13:08)

3 CVEs addressed in Bionic ESM (18.04 ESM), Focal (20.04 LTS)
5.4 20.04 GA, 18.04 HWE

[USN-6388-1] Linux kernel vulnerabilities (13:12)

9 CVEs addressed in Trusty ESM (14.04 ESM), Xenial ESM (16.04 ESM)
4.4 16.04 GA, 14.04 HWE

Goings on in Ubuntu Security Community

Highlights from LSS EU (13:29)

Hardware-backed Per-process Secrets - Matthew Garrett, Aurora
- Mark Esler described as a crystal clear explanation of how TPM works and proposes an automated attestation for confidential computing
Estimating Security Risk Through Repository Mining - Tamas K. Lengyel, Intel proposed that most common metrics don’t demonstrate code quality, except possibly percentage of cognitive complex functions
- cyclomatic complexity measured how hard to test - cognitive complexity tries to measure how hard to understand
  - premise is that if you can’t understand it, you can’t see the vulns
- intuitively makes sense, but relies on the ability actually measure cognitive complexity
  - and recent studies seem to show that the current cognitive complexity measurements are no better at accurately identifying code that is hard to understand than the more traditional methods of LOC or cyclomatic complexity
- Cognitive Complexity: A new way of measuring understandability white paper by G. Ann Campbell of SonarSource
- I missed this one but as Steve Beattie said, it does provide some things to think about in the context of the security reviews that the Ubuntu Security does as part of the MIR process (for a good overview of this, take a step back in time to Main inclusion review security code audits discussion with Seth Arnold from Episode 32)

Top 25 most stubborn weaknesses (17:13)

https://cwe.mitre.org/top25/archive/2023/2023_stubborn_weaknesses.html
MITRE 2023 CWE Top 25 Most Dangerous Software Weaknesses published from Episode 201
15 CWEs present in every one of the last 5 top 25 most dangerous lists from MITRE

CWE-ID	Description	2023 Rank
CWE-787	Out-of-bounds Write	1
CWE-79	Improper Neutralization of Input During Web Page Generation (‘Cross-site Scripting’)	2
CWE-89	Improper Neutralization of Special Elements used in an SQL Command (‘SQL Injection’)	3
CWE-416	Use After Free	4
CWE-78	Improper Neutralization of Special Elements used in an OS Command (‘OS Command Injection’)	5
CWE-20	Improper Input Validation	6
CWE-125	Out-of-bounds Read	7
CWE-22	Improper Limitation of a Pathname to a Restricted Directory (‘Path Traversal’)	8
CWE-352	Cross-Site Request Forgery (CSRF)	9
CWE-476	NULL Pointer Dereference	12
CWE-287	Improper Authentication	13
CWE-190	Integer Overflow or Wraparound	14
CWE-502	Deserialization of Untrusted Data	15
CWE-119	Improper Restriction of Operations within Bounds of a Memory Buffer	17
CWE-798	Use of Hard-coded Credentials	18

all fall into one of three different categories
- errors when processing of data from untrusted sources providing an initial entry point for compromise
- weaknesses from using languages that don’t provide strong memory safety guarantees
- poor security architecture / design choices
re memory safety - MITRE note that this has been coming down - CWE-119 (“Improper Restriction of Operations within Bounds of a Memory Buffer”) was once ranked 1 5 years ago, is now 17. Related (but not directly memory safety but more correctness) CWE-190 (“Integer Overflow or Wraparound”) was ranked 5, is now 7.
Really shows that if you are implementing any new code, choosing a language that is memory safe will help avoid a lot of the most prevalent security issues - clearly won’t help with lack of proper input validation or poor security architecture etc - but will cut out the most dangerous and most stubborn issues (OOB W, UAF etc)

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Ubuntu Security Podcast

Episode 210