vulnerability / NVI-00011713 / Revision 1
Sliver: Unauthenticated Memory Exhaustion Denial of Service in Sliver HTTP(S) Listener PNG Decoder
GitHub lists this reviewed advisory for github.com/BishopFox/sliver. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
github.com/BishopFox/sliver
source listed< 1.7.6
### Summary Sliver is vulnerable to a Denial of Service (DOS) attack because there is no cap in the size of a PNG file that can be sent to an open http listener and there is a small amount of possible nonces. This vulnerability lets the attacker completely max out the RAM of the machine running server, leading to a complete loss of availability. ### Details The first vulnerability is that the amount of possible nonces is 65,537. This is found in `server/encoders/encoders.go` ```go const ( EncoderModulus = uint64(65537) ) ``` The second vulnerability is there is no limit to how many pixels the PNG encoder will accept from an unauthenticated user. This is found in: `util/encoders/images.go` ```go func (p PNGEncoder) Encode(data []byte) ([]byte, error) { img := imageFromBytes(data) var buf bytes.Buffer encoder.Encode(&buf, img) return buf.Bytes(), nil } func (p PNGEncoder) Decode(data []byte) ([]byte, error) { buf := bytes.NewBuffer(data) img, err := png.Decode(buf) if err != nil { return nil, err } return bytesFromImage(img), nil } ``` ### PoC The first step to reproduce this vulnerability is building a docker container to make sure no harm i
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-663m-7x7m-g4fw ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
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