Sudo Baron Samedit - Local Privilege Escalation

Exploited in the wild. Listed by CISA on 2022-04-06; known to be used by ransomware.

highseverity

7.8CVSS score

100%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

Sudo before 1.9.5p2 contains an off-by-one error that can result in a heap-based buffer overflow, which allows privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character.

Impact

Attackers can escalate privileges to root, potentially leading to full system compromise.

Fix

Upgrade Sudo to version 1.9.5p2 or later that fixes the heap-based buffer overflow vulnerability.

How to confirm it

Positive when: contains "malloc(): memory corruption" and "Aborted (core dumped)"

Run it with nuclei: nuclei -id CVE-2021-3156 -u <target>

The full check

id: CVE-2021-3156

info:
  name: Sudo Baron Samedit - Local Privilege Escalation
  author: pussycat0x
  severity: high
  description: |
    Sudo before 1.9.5p2 contains an off-by-one error that can result in a heap-based buffer overflow, which allows privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character.
  remediation: |
    Upgrade Sudo to version 1.9.5p2 or later that fixes the heap-based buffer overflow vulnerability.
  impact: |
    Attackers can escalate privileges to root, potentially leading to full system compromise.
  reference:
    - https://medium.com/mii-cybersec/privilege-escalation-cve-2021-3156-new-sudo-vulnerability-4f9e84a9f435
    - https://blog.qualys.com/vulnerabilities-threat-research/2021/01/26/cve-2021-3156-heap-based-buffer-overflow-in-sudo-baron-samedit
    - https://infosecwriteups.com/baron-samedit-cve-2021-3156-tryhackme-76d7dedc3cff
    - http://packetstormsecurity.com/files/161160/Sudo-Heap-Based-Buffer-Overflow.html
    - http://packetstormsecurity.com/files/176932/glibc-syslog-Heap-Based-Buffer-Overflow.html
  classification:
    cvss-metrics: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 7.8
    cve-id: CVE-2021-3156
    cwe-id: CWE-193
    epss-score: 0.99962
    epss-percentile: 0.99975
    cpe: cpe:2.3:a:sudo_project:sudo:*:*:*:*:*:*:*:*
  metadata:
    verified: true
    vendor: sudo_project
    product: sudo
  tags: packetstorm,cve,cve2021,sudo,code,linux,privesc,local,kev,sudo_project,vkev,vuln

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      sudoedit -s '\' $(python3 -c 'print("A"*1000)')

    matchers:
      - type: word
        words:
          - "malloc(): memory corruption"
          - "Aborted (core dumped)"
        condition: and

References

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