spdystream SPDY/3 Frame Parser Denial of Service

The spdystream library, specifically versions 0.5.0 and earlier, contains a vulnerability in its SPDY/3 frame parser. This vulnerability allows a remote attacker to cause a denial-of-service (DoS) by sending specially crafted SPDY frames to a service that utilizes spdystream. The vulnerability stems from the lack of validation of attacker-controlled counts and lengths before memory allocation, leading to excessive memory usage and, ultimately, an out-of-memory crash. A single crafted SPDY control frame is sufficient to exhaust the process's memory. This issue was resolved in version 0.5.1. The affected package is github.com/moby/spdystream.

Attack Chain

1. The attacker establishes a SPDY connection with a service using the vulnerable spdystream library.
2. The attacker crafts a SPDY SETTINGS frame with a malicious numSettings value exceeding the frame length.
3. The vulnerable spdystream library receives the crafted SETTINGS frame.
4. The SETTINGS frame reader allocates memory based on the attacker-controlled numSettings without proper validation.
5. Alternatively, the attacker sends a zlib-compressed SPDY header block.
6. The vulnerable spdystream library decompresses the header block, resulting in attacker-controlled bytes interpreted as numHeaders.
7. The parseHeaderValueBlock function allocates an http.Header map of the specified numHeaders size without any upper bound, exhausting available memory.
8. The process crashes due to an out-of-memory error, causing a denial of service.

Impact

Any program accepting SPDY connections through the vulnerable spdystream library is susceptible. A successful attack allows a remote peer to crash the process with a single, specially crafted SPDY control frame. This leads to a denial-of-service condition, potentially impacting the availability of critical services. While the exact number of victims and sectors targeted remains unknown, the widespread use of SPDY and related protocols makes this a significant concern.

Recommendation

• Upgrade the github.com/moby/spdystream library to version 0.5.1 or later to patch the vulnerability (reference: Affected versions and Fix sections).
• Deploy a network intrusion detection system (NIDS) rule to detect SPDY frames with abnormally large numSettings values in SETTINGS frames (reference: Attack Chain step 2).
• Implement rate limiting for SPDY connections to mitigate the impact of potential DoS attacks (reference: Overview and Impact sections).
• Monitor application logs for out-of-memory errors related to spdystream to identify potential exploitation attempts (reference: Impact section).