CVE-2007-3499 in SlackRoll
Summary
by MITRE
SlackRoll before 8 accepts gpg exit codes other than 0 and 1 as evidence of a valid signature, which allows remote Slackware mirror sites or man-in-the-middle attackers to cause a denial of service (data inconsistency) or possibly install Trojan horse packages via malformed gpg signatures.
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Analysis
by VulDB Data Team • 09/04/2018
The vulnerability identified as CVE-2007-3499 affects SlackRoll versions prior to 8.0, a tool used for managing software packages in Slackware Linux distributions. This flaw resides in the GPG signature verification process where the application incorrectly interprets GPG exit codes beyond the standard 0 and 1 as valid signature indicators. The standard GPG behavior specifies that exit code 0 indicates a successful signature verification while exit code 1 typically signals a signature failure, yet SlackRoll's implementation extends this validation to include other exit codes, creating a security loophole.
The technical implementation flaw stems from improper error handling within SlackRoll's GPG verification routine. When GPG processes a signature, it returns specific exit codes that indicate the outcome of the verification process. Standard GPG implementations return exit code 0 for valid signatures and exit code 1 for invalid signatures, with other codes typically indicating various error conditions such as missing keys, malformed signatures, or other processing issues. SlackRoll's developers failed to properly validate these exit codes, leading to a situation where non-standard exit codes might be interpreted as successful verifications, effectively bypassing the signature validation mechanism.
This vulnerability creates significant operational risks for Slackware mirror sites and system administrators who rely on GPG signatures to ensure package integrity and authenticity. The impact extends beyond simple denial of service to potentially allow malicious actors to inject Trojan horse packages into the distribution. Attackers could exploit this weakness by crafting malformed GPG signatures that return exit codes which SlackRoll interprets as valid, thereby allowing unauthorized packages to be installed on systems. The vulnerability particularly affects man-in-the-middle attack scenarios where attackers can intercept and modify package data, using the flawed signature verification to bypass security controls.
The security implications of this vulnerability align with CWE-254, which addresses 'Security Features' weaknesses, specifically focusing on inadequate error handling and validation of security-relevant information. The flaw also relates to ATT&CK technique T1553.004, which covers 'Subvert Trust Controls: File and Directory Permissions Modification,' as it allows attackers to manipulate package verification processes. Additionally, this vulnerability demonstrates characteristics of T1499.004, 'Network Denial of Service,' where the improper handling of signature validation can lead to inconsistent data states and potential system instability.
Mitigation strategies should include upgrading to SlackRoll version 8.0 or later, which addresses the flawed GPG exit code handling. Organizations should also implement additional verification layers beyond GPG signatures, such as checksum validation or multiple signature verification methods. Network administrators should monitor for suspicious package installations and maintain updated security policies that account for such signature verification weaknesses. The vulnerability highlights the importance of proper error code validation in security-critical applications and underscores the need for adherence to established security protocols when implementing cryptographic verification mechanisms.