CVE-2005-1515 in Qmail
Summary
by MITRE
Integer signedness error in the qmail_put and substdio_put functions in qmail, when running on 64 bit platforms with a large amount of virtual memory, allows remote attackers to cause a denial of service and possibly execute arbitrary code via a large number of SMTP RCPT TO commands.
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Analysis
by VulDB Data Team • 07/03/2019
The vulnerability described in CVE-2005-1515 represents a critical integer signedness error within the qmail mail transfer agent that specifically manifests on 64-bit systems with substantial virtual memory configurations. This flaw resides in the qmail_put and substdio_put functions, which are fundamental components responsible for handling SMTP command processing and data buffering operations. The issue arises from the improper handling of signed integer values when processing large quantities of RCPT TO commands, creating a condition where the system's memory management becomes compromised due to incorrect assumptions about data type boundaries.
The technical exploitation of this vulnerability occurs through a carefully crafted sequence of SMTP RCPT TO commands that, when processed in large volumes, trigger the signed integer overflow condition. On 64-bit platforms, the memory addressing capabilities and data type representations differ significantly from 32-bit systems, allowing the signedness error to propagate through the system's memory management routines. When the qmail daemon processes these commands, the integer overflow causes unexpected behavior in memory allocation and buffer handling, potentially leading to memory corruption that can be leveraged for remote code execution or system instability.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as the integer signedness error creates opportunities for privilege escalation and arbitrary code execution. Attackers can exploit this weakness by sending numerous RCPT TO commands that cause the system to miscalculate memory requirements, potentially leading to buffer overflows or memory corruption that can be manipulated to execute malicious code with the privileges of the qmail process. This represents a significant security risk for email servers that rely on qmail as their primary mail transfer agent, particularly in environments where the mail server processes high volumes of email traffic.
The vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions, and demonstrates how improper handling of signed versus unsigned integers can lead to severe security implications. From an adversarial perspective, this flaw maps to ATT&CK technique T1190, which covers exploitation of remote services through buffer overflow conditions, and T1068, which involves the exploitation of local privilege escalation opportunities. Organizations running qmail on 64-bit systems should prioritize immediate patching of this vulnerability, as the combination of 64-bit architecture and large virtual memory configurations creates an ideal environment for exploitation. The recommended mitigation strategy involves applying the official qmail security patches that correct the integer signedness handling in the affected functions, along with implementing network-level restrictions that limit the number of RCPT TO commands that can be processed within a given timeframe to prevent exploitation attempts.
This vulnerability serves as a critical reminder of the importance of proper integer type handling in security-sensitive applications, particularly when dealing with memory management on 64-bit platforms where the boundary conditions between signed and unsigned integer operations can create exploitable conditions. The flaw demonstrates how seemingly minor implementation details in low-level system functions can have profound security implications when operating in specific environmental configurations.