Common Vulnerabilities and Exposures assigned an identifier CVE-2008-1390 to the following vulnerability: Asterisk Project Security Advisory - AST-2008-005 Due to the way that manager IDs are calculated, this 32-bit integer is likely to have a much larger than average number of 1s, which greatly reduces the number of guesses an attacker would have to make to successfully predict the manager ID, which is used across multiple HTTP queries to hold manager state. "The issue is the generation of session ids in the AsteriskGUI HTTP server. When using Glibc, the implementation and state of rand() and random() is shared. Asterisk uses random() to issue MD5 digest authentication challenges and rand() bitwise-ORed with a malloc'd pointer to generate AsteriskGUI session identifiers. An attacker can synchronize with random() by retrieving 32 successive challenges and predict all subsequent output of calls to random() and rand(). Because a pointer returned by malloc has at best 21 bits of entropy, the attacker will on average only need to guess 1448 session identifiers in order to steal an established session. "The crux of the problem is that under Glibc, the implementation of rand() and random() is shared. rand() is just an alias to random(). This means that they all come from the same randomizer with the same state. "A remote attacker can synchronize with all subsequent output of a remote system's random() state by just observing or retrieving 32 successive outputs. They can easily do this by generating 32 MD5 digest authentication challenges. At this point, they will be able to predict all subsequent output of random() and rand(). "The memory address returned by calloc() is also not sufficiently random. In practice, it will be in low memory, immediately following the executable. In addition, the buffer returned will be 8-byte aligned. This means that the high order 8 bits and low order 3 bits will always be zero. Finally, this value is bitwise ORed with the output of random(), so any bits that are set will be preserved. "An attacker will only have to guess 2^N session ids, where N is the number of zeros in the number return by random() between bit positions 3 and 24. On average, this will be 1448 guesses. "However, an attacker can do better than this by consuming challenges until the following number output by random() has many 1's in those significant bit positions." References: http://downloads.digium.com/pub/security/AST-2008-005.html Note: This issue is *not* fixed in upstream 1.4.18.1.
asterisk-1.4.18.1-1.fc8 has been submitted as an update for Fedora 8
asterisk-1.4.18.1-1.fc7 has been submitted as an update for Fedora 7
asterisk-1.4.18.1-1.fc8 has been pushed to the Fedora 8 stable repository. If problems still persist, please make note of it in this bug report.
asterisk-1.4.18.1-1.fc7 has been pushed to the Fedora 7 stable repository. If problems still persist, please make note of it in this bug report.
This issue was addressed in: Fedora: https://admin.fedoraproject.org/updates/F7/FEDORA-2008-2620 https://admin.fedoraproject.org/updates/F8/FEDORA-2008-2554