New Samba Bug Allows Remote Attackers to Execute Arbitrary Code as Root

Jan 31, 2022

Samba has issued software updates ^[1]
to address multiple security vulnerabilities that, if successfully
exploited, could allow remote attackers to execute arbitrary code
with the highest privileges on affected installations.

Chief among them is CVE-2021-44142 ^[2], which impacts ^[3]
all versions of Samba before 4.13.17 and concerns an out-of-bounds ^[4]
heap read/write vulnerability in the VFS module “vfs_fruit ^[5]” that provides
compatibility with Apple SMB clients.

Samba ^[6]
is a popular freeware implementation of the Server Message Block
(SMB) protocol that allows users to access files, printers, and
other commonly shared resources over a network.

“All versions of Samba prior to 4.13.17 are vulnerable to an
out-of-bounds heap read write vulnerability that allows remote
attackers to execute arbitrary code as root on affected Samba
installations that use the VFS module vfs_fruit,” the maintainers
said in an advisory published on January 31.

According to the CERT Coordination Center (CERT/CC ^[7]), the flaw also affects
widely used Linux distributions such as Red Hat ^[8], SUSE Linux, and
Ubuntu.

The vulnerability, rated 9.9 on the CVSS scale, has been
credited to security researcher Orange Tsai from DEVCORE, who last
year disclosed ^[9]
the widely-exploited flaws in Microsoft Exchange Server.
Additionally, the fix has been issued in Samba versions 4.14.12 and
4.15.5.

Also addressed by Samba are two additional flaws —

CVE-2021-44141 ^[10] (CVSS score: 4.2) –
Information leak via symlinks of existence of files or directories
outside of the exported share (Fixed in Samba version 4.15.5)
CVE-2022-0336 ^[11] (CVSS score: 3.1) –
Samba AD users with permission to write to an account can
impersonate arbitrary services (Fixed in Samba versions 4.13.17,
4.14.12, and 4.15.4)

Samba administrators are recommended to upgrade to these
releases or apply the patch as soon as possible to mitigate the
defect and thwart any potential attacks exploiting the
vulnerability.

References

^{^}
software
updates (www.samba.org)
^{^}
CVE-2021-44142
(www.samba.org)
^{^}
impacts
(bugzilla.samba.org)
^{^}
out-of-bounds
(cwe.mitre.org)
^{^}
vfs_fruit
(www.samba.org)
^{^}
Samba
(en.wikipedia.org)
^{^}
CERT/CC
(kb.cert.org)
^{^}
Red
Hat (access.redhat.com)
^{^}
disclosed
(thehackernews.com)
^{^}
CVE-2021-44141
(www.samba.org)
^{^}
CVE-2022-0336
(www.samba.org)

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OWASP TOP !0

Injection. Injection flaws, such as SQL, NoSQL, OS, and LDAP injection, occur when untrusted data is sent to an interpreter as part of a command or query. The attacker’s hostile data can trick the interpreter into executing unintended commands or accessing data without proper authorization. Broken Authentication. Application functions related to authentication and session management are often implemented incorrectly, allowing attackers to compromise passwords, keys, or session tokens, or to exploit other implementation flaws to assume other users’ identities temporarily or permanently. Sensitive Data Exposure. Many web applications and APIs do not properly protect sensitive data, such as financial, healthcare, and PII. Attackers may steal or modify such weakly protected data to conduct credit card fraud, identity theft, or other crimes. Sensitive data may be compromised without extra protection, such as encryption at rest or in transit, and requires special precautions when exchanged with the browser. XML External Entities (XXE). Many older or poorly configured XML processors evaluate external entity references within XML documents. External entities can be used to disclose internal files using the file URI handler, internal file shares, internal port scanning, remote code execution, and denial of service attacks. Broken Access Control. Restrictions on what authenticated users are allowed to do are often not properly enforced. Attackers can exploit these flaws to access unauthorized functionality and/or data, such as access other users’ accounts, view sensitive files, modify other users’ data, change access rights, etc. Security Misconfiguration. Security misconfiguration is the most commonly seen issue. This is commonly a result of insecure default configurations, incomplete or ad hoc configurations, open cloud storage, misconfigured HTTP headers, and verbose error messages containing sensitive information. Not only must all operating systems, frameworks, libraries, and applications be securely configured, but they must be patched/upgraded in a timely fashion. Cross-Site Scripting XSS. XSS flaws occur whenever an application includes untrusted data in a new web page without proper validation or escaping, or updates an existing web page with user-supplied data using a browser API that can create HTML or JavaScript. XSS allows attackers to execute scripts in the victim’s browser which can hijack user sessions, deface web sites, or redirect the user to malicious sites. Insecure Deserialization. Insecure deserialization often leads to remote code execution. Even if deserialization flaws do not result in remote code execution, they can be used to perform attacks, including replay attacks, injection attacks, and privilege escalation attacks. Using Components with Known Vulnerabilities. Components, such as libraries, frameworks, and other software modules, run with the same privileges as the application. If a vulnerable component is exploited, such an attack can facilitate serious data loss or server takeover. Applications and APIs using components with known vulnerabilities may undermine application defenses and enable various attacks and impacts. Insufficient Logging & Monitoring. Insufficient logging and monitoring, coupled with missing or ineffective integration with incident response, allows attackers to further attack systems, maintain persistence, pivot to more systems, and tamper, extract, or destroy data. Most breach studies show time to detect a breach is over 200 days, typically detected by external parties rather than internal processes or monitoring.

New Samba Bug Allows Remote Attackers to Execute Arbitrary Code as Root

References

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