Overview
The uClibc and uClibc-ng libraries are vulnerable to DNS cache poisoning due to the use of predicatble DNS transaction IDs when making DNS requests. This vulnerability can allow an attacker to perform DNS cache poisoning attacks against a vulnerable environment.
Description
The uClibc and the Uclibc-ng software are lightweight C standard libraries intended for use in embedded systems and mobile devices. The uClibc library has not been updated since May of 2012. The newer uClibc-ng is the currently maintained fork of uClibc, as announced on the OpenWRT mailing list in July 2014.
Researchers at the Nozomi Networks Security Research Team discovered that all existing versions of uClibc and uClibc-ng libraries are vulnerable to DNS cache poisoning. These libraries do not employ any randomization in the DNS Transaction ID (DNS TXID) field when creating a new DNS request. This can allow an attacker to send maliciously crafted DNS packets to corrupt the DNS cache with invalid entries and redirect users to arbitrary sites. As uClibc and uClibc-ng are used in devices such as home routers and firewalls, an attacker can perform attacks against multiple users in a shared network environment that relies on DNS responses from the vulnerable device.
The DNS cache poisoning scenarios and defenses are discussed in IETF RFC5452.
Impact
The lack of DNS response validation can allow an attacker to use unsolicited DNS responses to poison the DNS cache and redirect users to malicious sites.
Solution
Develop and apply updates
If your vendor has developed a patched version of software to address this issue, apply the updates ..
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