CVE-2012-4507 in claws-mail
Summary
by MITRE
The strchr function in procmime.c in Claws Mail (aka claws-mail) 3.8.1 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via a crafted email.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability identified as CVE-2012-4507 affects Claws Mail version 3.8.1, specifically within the procmime.c component where the strchr function is implemented. This flaw represents a classic null pointer dereference issue that can be exploited remotely through carefully crafted email content. The vulnerability resides in the email processing logic that handles MIME (Multipurpose Internet Mail Extensions) content, making it particularly dangerous in email client environments where users frequently receive untrusted messages from external sources.
The technical implementation of this vulnerability stems from improper input validation within the procmime.c file where the strchr function attempts to process email headers or content without adequate null pointer checks. When a maliciously crafted email contains specific malformed MIME structures or header values, the strchr function receives a null pointer as input and subsequently attempts to dereference it, leading to an immediate crash of the application. This behavior aligns with CWE-476 which specifically addresses NULL pointer dereference vulnerabilities, and represents a direct violation of secure coding practices that require all pointer inputs to be validated before use.
From an operational perspective, this vulnerability creates a significant denial of service risk for Claws Mail users who may encounter crafted emails from attackers or compromised systems. The remote exploitation capability means that simply receiving a malicious email can cause the application to crash, potentially resulting in loss of unsaved work and disruption of email communication. The impact extends beyond individual users to potential organizational risks, as attackers could leverage this vulnerability to systematically disrupt email services or target specific users within an organization. This vulnerability also maps to ATT&CK technique T1204.002 which involves user execution of malicious content through email attachments or links, though in this case the attack vector is more subtle and occurs during the email parsing process itself.
The mitigation strategies for this vulnerability should include immediate patching of Claws Mail to version 3.8.2 or later where the null pointer dereference has been corrected. System administrators should also implement email filtering rules that can identify and quarantine suspicious MIME structures, though this approach may not be comprehensive given the subtle nature of the attack. Additionally, users should be educated about the risks of opening emails from untrusted sources and the importance of keeping email client software updated. The vulnerability demonstrates the critical importance of input validation in email processing components, as highlighted by CWE-129 and CWE-707 which emphasize proper bounds checking and validation of external inputs. Organizations should also consider implementing sandboxing techniques for email processing or using email security appliances that can detect and prevent such attacks before they reach end-user systems.