CVE-2014-1569

What it actually does

The definite_length_decoder in NSS quickder.c fails to validate ASN.1 DER length encodings, permitting arbitrary-length sequences such as an encoding of 0x00 that bypasses intended bounds checks in SEC_QuickDERDecodeItem and enables data smuggling.

Why it matters to the business

Systems relying on NSS for cryptographic parsing face risk of data integrity violations and unauthorized information disclosure in TLS, certificate handling, and related secure protocols, with elevated urgency due to public exploit availability for over a decade.

How an attack unfolds

An attacker crafts a network payload containing ASN.1 DER structures with an improperly formed length field consisting of a long byte sequence representing 0x00, transmits it to a service using vulnerable NSS, and the decoder misinterprets the structure to smuggle additional attacker-controlled data past validation.

How to fix it

Upgrade Mozilla NSS to version 3.16.2.4 or 3.17.3 or later; rebuild and redeploy all dependent applications; disable unnecessary ASN.1 parsing paths where feasible until patches are applied.

How to confirm the fix worked

Inventory NSS shared libraries and verify versions are at or above 3.16.2.4 / 3.17.3; run regression tests using known-malformed DER length vectors against SEC_QuickDERDecodeItem; confirm absence of the vulnerable quickder.c code path.

Typical attack path

1. Locate network-accessible service or application linked to vulnerable NSS
2. Generate ASN.1 DER blob with oversized or malformed length encoding for value 0x00
3. Deliver the payload via TLS handshake, certificate exchange, or other NSS-parsed input
4. Trigger SEC_QuickDERDecodeItem to process the structure and achieve smuggling
5. Leverage smuggled data for further protocol manipulation or information disclosure

How to detect it

Search application and TLS logs for parsing anomalies around ASN.1 DER structures, repeated SEC_QuickDERDecodeItem calls with unusual length values, or unexpected data following a zero-length encoding; correlate with network captures containing long byte runs encoding 0x00.

• SEC_QuickDERDecodeItem
• definite_length_decoder
• quickder.c
• arbitrary-length encoding of 0x00

What your security team should do

• Prioritize patching NSS across all products given public exploit maturity and long exposure window
• Scan for and replace any statically linked or bundled NSS copies older than the fixed releases
• Implement network-level filtering for anomalous ASN.1 DER length fields where possible
• Review certificate and TLS handling code for reliance on the affected decoder