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

This week in Ubuntu Security Updates88 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 whenverifying the signature on a SAML document, failed to configure the library toonly use the X509 certificate for validation - since presumably an attackercould intercept the SAML token, and replace the X509 cert with a differenttype of signature which would then be trusted by the xmlsec library and allowthe 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 Episode206 - 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 thatthis 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) + CVE-2023-4863 + CVE-2023-4584 + CVE-2023-4581 + CVE-2023-4575 + CVE-2023-4574 + CVE-2023-4573 * 102.15.1 - libwebp issue above plus various other issues - various UAFs,missing .xll files from standard blocklist that warns users when downloadingexecutables - 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) + CVE-2023-24021 + CVE-2022-48279 + CVE-2021-42717 * CPU-based DoS when parsing excessively nested JSON objects (needs to betens-of-thousands deep) * Mishandling of NUL byte in file uploads - would parse the filename as a stringbut if it contained an embedded NUL byte then filename would be truncated andhence could result in a buffer overread or the ability to bypass the webapplication 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 totrigger - 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 thereis a privileged user using the in-built monitoring interface of dbus tomonitor the traffic - so low chance of being able to trigger this and theoutcome 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 abuffer 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 OOBread -> 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 unicodecharacter - 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 ormulti-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) + CVE-2022-47695 + CVE-2022-44840 + CVE-2020-35342 + CVE-2022-45703 + CVE-2021-46174 + CVE-2020-19726 + CVE-2020-21490 + CVE-2020-19724 * 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) + CVE-2020-8287 + CVE-2020-8265 + CVE-2020-8174 + CVE-2019-15606 + CVE-2019-15605 + CVE-2019-15604 * abort when sending a crafted X509 certificate -> DoS * 2 different HTTP request smuggling attacks * possible bypass of HTTP authorization since would include whitespace in HTTPheaders * 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) + CVE-2023-38429 + CVE-2023-38428 + CVE-2023-38426 + CVE-2023-3212 + CVE-2023-31084 + CVE-2023-2898 + CVE-2023-21255 + CVE-2022-48425 * 5.15 * same set of vulns from [USN-6350-1, USN-6351-1, USN-6339-2, USN-6339-3] Linuxkernel vulnerabilities

[USN-6383-1] Linux kernel vulnerabilities (11:15)* 5 CVEs addressed in Jammy (22.04 LTS), Lunar (23.04) + CVE-2023-4569 + CVE-2023-4128 + CVE-2023-40283 + CVE-2023-21264 + CVE-2023-20588 * 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 couldthen 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 usernamespace * Memory leak in netfilter - also able to be abused by an unprivileged user in auser 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 auser namespace

[USN-6385-1] Linux kernel (OEM) vulnerabilities (12:37)* 37 CVEs addressed in Jammy (22.04 LTS) + CVE-2023-4569 + CVE-2023-4273 + CVE-2023-4128 + CVE-2023-40283 + CVE-2023-4015 + CVE-2023-4004 + CVE-2023-3995 + CVE-2023-3863 + CVE-2023-3777 + CVE-2023-3776 + CVE-2023-3611 + CVE-2023-3610 + CVE-2023-3609 + CVE-2023-3390 + CVE-2023-32269 + CVE-2023-3220 + CVE-2023-31436 + CVE-2023-3141 + CVE-2023-3090 + CVE-2023-2898 + CVE-2023-28466 + CVE-2023-28328 + CVE-2023-2269 + CVE-2023-2235 + CVE-2023-2163 + CVE-2023-2162 + CVE-2023-20593 + CVE-2023-2002 + CVE-2023-1611 + CVE-2023-1380 + CVE-2023-1206 + CVE-2023-4194 + CVE-2023-1076 + CVE-2023-1075 + CVE-2023-0458 + CVE-2022-4269 + CVE-2022-27672 * 6.0 OEM * All the previously mentioned vulns plus a heap more - kudos to OEM team andTimo 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) + CVE-2023-4569 + CVE-2023-4128 + CVE-2023-40283 + CVE-2023-20588 * 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) + CVE-2023-4128 + CVE-2023-40283 + CVE-2023-20588 * 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) + CVE-2023-4459 + CVE-2023-4387 + CVE-2023-4385 + CVE-2023-4128 + CVE-2023-40283 + CVE-2023-3863 + CVE-2023-32269 + CVE-2023-3212 + CVE-2022-40982 * 4.4 16.04 GA, 14.04 HWE

Goings on in Ubuntu Security CommunityHighlights 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 andproposes an automated attestation for confidential computing * Estimating Security Risk Through Repository Mining - Tamas K. Lengyel, Intelproposed that most common metrics don’t demonstrate code quality, exceptpossibly percentage of cognitive complex functions* + cyclomatic complexity measured how hard to test - cognitive complexitytries 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 measurecognitive complexity - and recent studies seem to show that the current cognitive complexitymeasurements are no better at accurately identifying code that is hardto understand than the more traditional methods of LOC or cyclomaticcomplexity + 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 tothink about in the context of the security reviews that the Ubuntu Securitydoes as part of the MIR process (for a good overview of this, take a stepback in time to Main inclusion review security code audits discussion withSeth 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 initialentry point for compromise
  • weaknesses from using languages that don’t provide strong memory safetyguarantees
  • 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”) wasonce ranked 1 5 years ago, is now 17. Related (but not directly memory safetybut 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 languagethat is memory safe will help avoid a lot of the most prevalent securityissues - clearly won’t help with lack of proper input validation or poorsecurity architecture etc - but will cut out the most dangerous and moststubborn issues (OOB W, UAF etc)

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