CVE-2008-0166 was caused by a Debian-specific change that made OpenSSL-generated key material predictable in affected releases. Debian required regeneration of both weak OpenSSH user keys and host keys and added blacklist detection. The consequences differ: a recovered user private key may authenticate to accounts that trust it, while a recovered host private key can support server impersonation or attacks on host identity. Other low-entropy or duplicated-device-key findings require product- and firmware-specific evidence.
# identify key type and size
ssh-keygen -lf authorized_keys # fingerprint and bit length
# on systems retaining Debian's blacklist utility, check keys against known weak sets
ssh-vulnkey target.pub
# interpret a match according to whether target.pub is a user or host key
Exploitation notes#
- Known CVE-2008-0166 public keys can be compared with precomputed weak-key sets; impact then depends on how that key is used and trusted.
- RSA keys below 2048 bits are obsolete under current security-strength guidance, but that does not mean an arbitrary 1024-bit RSA modulus is presently practical to factor.
- DSA has separate algorithm and parameter concerns; identify the exact problem instead of treating every legacy DSA key as factorable.
- Repeated embedded-device keys are a product-specific finding. A duplicated host key affects server identity; a duplicated authorized client key can affect login authorization.