CVE-2022-2127 in Samba
Summary
by MITRE • 07/20/2023
An out-of-bounds read vulnerability was found in Samba due to insufficient length checks in winbindd_pam_auth_crap.c. When performing NTLM authentication, the client replies to cryptographic challenges back to the server. These replies have variable lengths, and Winbind fails to check the lan manager response length. When Winbind is used for NTLM authentication, a maliciously crafted request can trigger an out-of-bounds read in Winbind, possibly resulting in a crash.
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Analysis
by VulDB Data Team • 07/26/2025
The vulnerability identified as CVE-2022-2127 represents a critical out-of-bounds read flaw within the Samba implementation that specifically affects the winbindd_pam_auth_crap.c component. This issue manifests during NTLM authentication processes where the system fails to properly validate the length of cryptographic challenge responses. The vulnerability stems from insufficient input validation mechanisms that should have enforced strict boundaries on the lan manager response data. When Samba processes authentication requests through winbindd, it encounters a scenario where the client's NTLM challenge response contains variable length data that is not adequately constrained by length checks within the authentication module. This particular flaw exists within the PAM authentication framework integration of Samba's winbind daemon, creating a potential attack surface that adversaries can exploit through carefully crafted malicious requests.
The technical exploitation of this vulnerability occurs when a malicious actor submits a specially constructed NTLM authentication request that contains an oversized lan manager response field. The winbindd_pam_auth_crap.c module lacks proper validation of the response length before processing the data, allowing the system to attempt to read memory locations beyond the allocated buffer boundaries. This out-of-bounds memory access can result in unpredictable behavior including program crashes, memory corruption, or potentially more severe consequences depending on the execution environment. The vulnerability specifically targets the winbind daemon's handling of NTLM authentication flows where the lan manager response is processed without adequate length verification, creating a direct path for attackers to trigger memory access violations.
From an operational standpoint, this vulnerability poses significant risks to systems relying on Samba for authentication services, particularly those utilizing winbind for NTLM authentication. The out-of-bounds read condition can lead to service disruption through crashes, potentially allowing attackers to perform denial-of-service attacks against critical authentication infrastructure. Systems where winbind is configured to handle NTLM authentication requests become vulnerable to exploitation, especially in environments where external authentication is required or where Samba serves as a domain controller or member server. The impact extends beyond simple service availability as the memory corruption could potentially be leveraged to execute arbitrary code or escalate privileges depending on the system configuration and the specific execution context of the winbind process.
The vulnerability aligns with CWE-129, which addresses insufficient input length validation, and represents a classic example of improper input validation that leads to memory safety issues. From an ATT&CK framework perspective, this vulnerability could be categorized under T1566 for initial access through credential dumping or T1078 for valid accounts usage, depending on how it's exploited within a broader attack chain. Organizations should implement immediate mitigations including applying the vendor-provided patches, configuring proper input validation for authentication requests, and monitoring for suspicious authentication patterns that might indicate exploitation attempts. Network segmentation and access controls should be strengthened around Samba servers to limit exposure, while regular security assessments should verify that all winbind components properly validate input lengths before processing authentication responses. The remediation approach must focus on ensuring that all cryptographic challenge response fields undergo strict length validation before any memory operations are performed, thereby preventing the out-of-bounds read conditions that enable this vulnerability to be exploited effectively.